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diff --git a/Source/JavaScriptCore/runtime/JSArray.h b/Source/JavaScriptCore/runtime/JSArray.h
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+/*
+ *  Copyright (C) 1999-2000 Harri Porten (porten@kde.org)
+ *  Copyright (C) 2003, 2007, 2008, 2009, 2012, 2015 Apple Inc. All rights reserved.
+ *
+ *  This library is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU Lesser General Public
+ *  License as published by the Free Software Foundation; either
+ *  version 2 of the License, or (at your option) any later version.
+ *
+ *  This library is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ *  Lesser General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public
+ *  License along with this library; if not, write to the Free Software
+ *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ */
+
+#ifndef JSArray_h
+#define JSArray_h
+
+#include "ArrayConventions.h"
+#include "ButterflyInlines.h"
+#include "JSObject.h"
+
+namespace JSC {
+
+class JSArray;
+class LLIntOffsetsExtractor;
+
+class JSArray : public JSNonFinalObject {
+    friend class LLIntOffsetsExtractor;
+    friend class Walker;
+    friend class JIT;
+
+public:
+    typedef JSNonFinalObject Base;
+    static const unsigned StructureFlags = Base::StructureFlags | OverridesGetOwnPropertySlot | OverridesGetPropertyNames;
+
+    static size_t allocationSize(size_t inlineCapacity)
+    {
+        ASSERT_UNUSED(inlineCapacity, !inlineCapacity);
+        return sizeof(JSArray);
+    }
+        
+protected:
+    explicit JSArray(VM& vm, Structure* structure, Butterfly* butterfly)
+        : JSNonFinalObject(vm, structure, butterfly)
+    {
+    }
+
+public:
+    static JSArray* create(VM&, Structure*, unsigned initialLength = 0);
+    static JSArray* createWithButterfly(VM&, Structure*, Butterfly*);
+
+    // tryCreateUninitialized is used for fast construction of arrays whose size and
+    // contents are known at time of creation. Clients of this interface must:
+    //   - null-check the result (indicating out of memory, or otherwise unable to allocate vector).
+    //   - call 'initializeIndex' for all properties in sequence, for 0 <= i < initialLength.
+    static JSArray* tryCreateUninitialized(VM&, Structure*, unsigned initialLength);
+
+    JS_EXPORT_PRIVATE static bool defineOwnProperty(JSObject*, ExecState*, PropertyName, const PropertyDescriptor&, bool throwException);
+
+    JS_EXPORT_PRIVATE static bool getOwnPropertySlot(JSObject*, ExecState*, PropertyName, PropertySlot&);
+
+    DECLARE_EXPORT_INFO;
+
+    // OK if we know this is a JSArray, but not if it could be an object of a derived class; for RuntimeArray this always returns 0.
+    unsigned length() const { return getArrayLength(); }
+
+    // OK to use on new arrays, but not if it might be a RegExpMatchArray or RuntimeArray.
+    JS_EXPORT_PRIVATE bool setLength(ExecState*, unsigned, bool throwException = false);
+
+    JS_EXPORT_PRIVATE void push(ExecState*, JSValue);
+    JS_EXPORT_PRIVATE JSValue pop(ExecState*);
+
+    JSArray* fastSlice(ExecState&, unsigned startIndex, unsigned count);
+
+    static IndexingType fastConcatType(VM& vm, JSArray& firstArray, JSArray& secondArray)
+    {
+        IndexingType type = firstArray.indexingType();
+        if (type != secondArray.indexingType())
+            return NonArray;
+        if (type != ArrayWithDouble && type != ArrayWithInt32 && type != ArrayWithContiguous)
+            return NonArray;
+        if (firstArray.structure(vm)->holesMustForwardToPrototype(vm)
+            || secondArray.structure(vm)->holesMustForwardToPrototype(vm))
+            return NonArray;
+        return type;
+    }
+    EncodedJSValue fastConcatWith(ExecState&, JSArray&);
+
+    enum ShiftCountMode {
+        // This form of shift hints that we're doing queueing. With this assumption in hand,
+        // we convert to ArrayStorage, which has queue optimizations.
+        ShiftCountForShift,
+            
+        // This form of shift hints that we're just doing care and feeding on an array that
+        // is probably typically used for ordinary accesses. With this assumption in hand,
+        // we try to preserve whatever indexing type it has already.
+        ShiftCountForSplice
+    };
+
+    bool shiftCountForShift(ExecState* exec, unsigned startIndex, unsigned count)
+    {
+        return shiftCountWithArrayStorage(exec->vm(), startIndex, count, ensureArrayStorage(exec->vm()));
+    }
+    bool shiftCountForSplice(ExecState* exec, unsigned& startIndex, unsigned count)
+    {
+        return shiftCountWithAnyIndexingType(exec, startIndex, count);
+    }
+    template<ShiftCountMode shiftCountMode>
+    bool shiftCount(ExecState* exec, unsigned& startIndex, unsigned count)
+    {
+        switch (shiftCountMode) {
+        case ShiftCountForShift:
+            return shiftCountForShift(exec, startIndex, count);
+        case ShiftCountForSplice:
+            return shiftCountForSplice(exec, startIndex, count);
+        default:
+            CRASH();
+            return false;
+        }
+    }
+        
+    bool unshiftCountForShift(ExecState* exec, unsigned startIndex, unsigned count)
+    {
+        return unshiftCountWithArrayStorage(exec, startIndex, count, ensureArrayStorage(exec->vm()));
+    }
+    bool unshiftCountForSplice(ExecState* exec, unsigned startIndex, unsigned count)
+    {
+        return unshiftCountWithAnyIndexingType(exec, startIndex, count);
+    }
+    template<ShiftCountMode shiftCountMode>
+    bool unshiftCount(ExecState* exec, unsigned startIndex, unsigned count)
+    {
+        switch (shiftCountMode) {
+        case ShiftCountForShift:
+            return unshiftCountForShift(exec, startIndex, count);
+        case ShiftCountForSplice:
+            return unshiftCountForSplice(exec, startIndex, count);
+        default:
+            CRASH();
+            return false;
+        }
+    }
+
+    JS_EXPORT_PRIVATE void fillArgList(ExecState*, MarkedArgumentBuffer&);
+    JS_EXPORT_PRIVATE void copyToArguments(ExecState*, VirtualRegister firstElementDest, unsigned offset, unsigned length);
+
+    static Structure* createStructure(VM& vm, JSGlobalObject* globalObject, JSValue prototype, IndexingType indexingType)
+    {
+        return Structure::create(vm, globalObject, prototype, TypeInfo(ObjectType, StructureFlags), info(), indexingType);
+    }
+        
+protected:
+    static void put(JSCell*, ExecState*, PropertyName, JSValue, PutPropertySlot&);
+
+    static bool deleteProperty(JSCell*, ExecState*, PropertyName);
+    JS_EXPORT_PRIVATE static void getOwnNonIndexPropertyNames(JSObject*, ExecState*, PropertyNameArray&, EnumerationMode);
+
+private:
+    bool isLengthWritable()
+    {
+        ArrayStorage* storage = arrayStorageOrNull();
+        if (!storage)
+            return true;
+        SparseArrayValueMap* map = storage->m_sparseMap.get();
+        return !map || !map->lengthIsReadOnly();
+    }
+        
+    bool shiftCountWithAnyIndexingType(ExecState*, unsigned& startIndex, unsigned count);
+    JS_EXPORT_PRIVATE bool shiftCountWithArrayStorage(VM&, unsigned startIndex, unsigned count, ArrayStorage*);
+
+    bool unshiftCountWithAnyIndexingType(ExecState*, unsigned startIndex, unsigned count);
+    bool unshiftCountWithArrayStorage(ExecState*, unsigned startIndex, unsigned count, ArrayStorage*);
+    bool unshiftCountSlowCase(VM&, bool, unsigned);
+
+    bool setLengthWithArrayStorage(ExecState*, unsigned newLength, bool throwException, ArrayStorage*);
+    void setLengthWritable(ExecState*, bool writable);
+};
+
+inline Butterfly* createContiguousArrayButterfly(VM& vm, JSCell* intendedOwner, unsigned length, unsigned& vectorLength)
+{
+    IndexingHeader header;
+    vectorLength = std::max(length, BASE_VECTOR_LEN);
+    header.setVectorLength(vectorLength);
+    header.setPublicLength(length);
+    Butterfly* result = Butterfly::create(
+        vm, intendedOwner, 0, 0, true, header, vectorLength * sizeof(EncodedJSValue));
+    return result;
+}
+
+inline Butterfly* createArrayButterfly(VM& vm, JSCell* intendedOwner, unsigned initialLength)
+{
+    Butterfly* butterfly = Butterfly::create(
+        vm, intendedOwner, 0, 0, true, baseIndexingHeaderForArray(initialLength),
+        ArrayStorage::sizeFor(BASE_VECTOR_LEN));
+    ArrayStorage* storage = butterfly->arrayStorage();
+    storage->m_indexBias = 0;
+    storage->m_sparseMap.clear();
+    storage->m_numValuesInVector = 0;
+    return butterfly;
+}
+
+Butterfly* createArrayButterflyInDictionaryIndexingMode(
+    VM&, JSCell* intendedOwner, unsigned initialLength);
+
+inline JSArray* JSArray::create(VM& vm, Structure* structure, unsigned initialLength)
+{
+    Butterfly* butterfly;
+    if (LIKELY(!hasAnyArrayStorage(structure->indexingType()))) {
+        ASSERT(
+            hasUndecided(structure->indexingType())
+            || hasInt32(structure->indexingType())
+            || hasDouble(structure->indexingType())
+            || hasContiguous(structure->indexingType()));
+        unsigned vectorLength;
+        butterfly = createContiguousArrayButterfly(vm, 0, initialLength, vectorLength);
+        ASSERT(initialLength < MIN_ARRAY_STORAGE_CONSTRUCTION_LENGTH);
+        if (hasDouble(structure->indexingType())) {
+            for (unsigned i = 0; i < vectorLength; ++i)
+                butterfly->contiguousDouble()[i] = PNaN;
+        }
+    } else {
+        ASSERT(
+            structure->indexingType() == ArrayWithSlowPutArrayStorage
+            || structure->indexingType() == ArrayWithArrayStorage);
+        butterfly = createArrayButterfly(vm, 0, initialLength);
+    }
+
+    return createWithButterfly(vm, structure, butterfly);
+}
+
+inline JSArray* JSArray::tryCreateUninitialized(VM& vm, Structure* structure, unsigned initialLength)
+{
+    unsigned vectorLength = std::max(BASE_VECTOR_LEN, initialLength);
+    if (vectorLength > MAX_STORAGE_VECTOR_LENGTH)
+        return 0;
+        
+    Butterfly* butterfly;
+    if (LIKELY(!hasAnyArrayStorage(structure->indexingType()))) {
+        ASSERT(
+            hasUndecided(structure->indexingType())
+            || hasInt32(structure->indexingType())
+            || hasDouble(structure->indexingType())
+            || hasContiguous(structure->indexingType()));
+
+        void* temp;
+        if (!vm.heap.tryAllocateStorage(0, Butterfly::totalSize(0, 0, true, vectorLength * sizeof(EncodedJSValue)), &temp))
+            return 0;
+        butterfly = Butterfly::fromBase(temp, 0, 0);
+        butterfly->setVectorLength(vectorLength);
+        butterfly->setPublicLength(initialLength);
+        if (hasDouble(structure->indexingType())) {
+            for (unsigned i = initialLength; i < vectorLength; ++i)
+                butterfly->contiguousDouble()[i] = PNaN;
+        }
+    } else {
+        void* temp;
+        if (!vm.heap.tryAllocateStorage(0, Butterfly::totalSize(0, 0, true, ArrayStorage::sizeFor(vectorLength)), &temp))
+            return 0;
+        butterfly = Butterfly::fromBase(temp, 0, 0);
+        *butterfly->indexingHeader() = indexingHeaderForArray(initialLength, vectorLength);
+        ArrayStorage* storage = butterfly->arrayStorage();
+        storage->m_indexBias = 0;
+        storage->m_sparseMap.clear();
+        storage->m_numValuesInVector = initialLength;
+    }
+
+    return createWithButterfly(vm, structure, butterfly);
+}
+
+inline JSArray* JSArray::createWithButterfly(VM& vm, Structure* structure, Butterfly* butterfly)
+{
+    JSArray* array = new (NotNull, allocateCell<JSArray>(vm.heap)) JSArray(vm, structure, butterfly);
+    array->finishCreation(vm);
+    return array;
+}
+
+JSArray* asArray(JSValue);
+
+inline JSArray* asArray(JSCell* cell)
+{
+    ASSERT(cell->inherits(JSArray::info()));
+    return jsCast<JSArray*>(cell);
+}
+
+inline JSArray* asArray(JSValue value)
+{
+    return asArray(value.asCell());
+}
+
+inline bool isJSArray(JSCell* cell) { return cell->classInfo() == JSArray::info(); }
+inline bool isJSArray(JSValue v) { return v.isCell() && isJSArray(v.asCell()); }
+
+inline JSArray* constructArray(ExecState* exec, Structure* arrayStructure, const ArgList& values)
+{
+    VM& vm = exec->vm();
+    unsigned length = values.size();
+    JSArray* array = JSArray::tryCreateUninitialized(vm, arrayStructure, length);
+
+    // FIXME: we should probably throw an out of memory error here, but
+    // when making this change we should check that all clients of this
+    // function will correctly handle an exception being thrown from here.
+    RELEASE_ASSERT(array);
+
+    for (unsigned i = 0; i < length; ++i)
+        array->initializeIndex(vm, i, values.at(i));
+    return array;
+}
+    
+inline JSArray* constructArray(ExecState* exec, Structure* arrayStructure, const JSValue* values, unsigned length)
+{
+    VM& vm = exec->vm();
+    JSArray* array = JSArray::tryCreateUninitialized(vm, arrayStructure, length);
+
+    // FIXME: we should probably throw an out of memory error here, but
+    // when making this change we should check that all clients of this
+    // function will correctly handle an exception being thrown from here.
+    RELEASE_ASSERT(array);
+
+    for (unsigned i = 0; i < length; ++i)
+        array->initializeIndex(vm, i, values[i]);
+    return array;
+}
+
+inline JSArray* constructArrayNegativeIndexed(ExecState* exec, Structure* arrayStructure, const JSValue* values, unsigned length)
+{
+    VM& vm = exec->vm();
+    JSArray* array = JSArray::tryCreateUninitialized(vm, arrayStructure, length);
+
+    // FIXME: we should probably throw an out of memory error here, but
+    // when making this change we should check that all clients of this
+    // function will correctly handle an exception being thrown from here.
+    RELEASE_ASSERT(array);
+
+    for (int i = 0; i < static_cast<int>(length); ++i)
+        array->initializeIndex(vm, i, values[-i]);
+    return array;
+}
+
+} // namespace JSC
+
+#endif // JSArray_h