https://bugs.webkit.org/show_bug.cgi?id=120333

Reviewed by Geoffrey Garen.

Source/JavaScriptCore:

Implement support for the ES6 Map type and related classes.

* JavaScriptCore.xcodeproj/project.pbxproj:
* heap/CopyToken.h: Add a new token to track copying the backing store
* runtime/CommonIdentifiers.h: Add new identifiers
* runtime/JSGlobalObject.cpp:
* runtime/JSGlobalObject.h:
    Add new structures and prototypes

* runtime/JSMap.cpp: Added.
* runtime/JSMap.h: Added.
    New JSMap class to represent a Map instance

* runtime/MapConstructor.cpp: Added.
* runtime/MapConstructor.h: Added.
    The Map constructor

* runtime/MapData.cpp: Added.
* runtime/MapData.h: Added.
    The most interesting data structure.  The roughly corresponds
    to the ES6 notion of MapData.  It provides the core JSValue->JSValue
    map implementation.  We implement it using 2 hashtables and a flat
    table.  Due to the different semantics of string comparisons vs.
    all others we need have one map keyed by String and the other by
    generic JSValue.  The actual table is represented more or less
    exactly as described in the ES6 draft - a single contiguous list of
    key/value pairs.  The entire map could be achieved with just this
    table, however we need the HashMaps in order to maintain O(1) lookup.

    Deleted values are simply cleared as the draft says, however the
    implementation compacts the storage on copy as long as the are no
    active iterators.

* runtime/MapPrototype.cpp: Added.
* runtime/MapPrototype.h: Added.
    Implement Map prototype functions

* runtime/VM.cpp:
    Add new structures.

LayoutTests:

Tests

* fast/js/basic-map-expected.txt: Added.
* fast/js/basic-map.html: Added.
* fast/js/script-tests/basic-map.js: Added.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@154861 268f45cc-cd09-0410-ab3c-d52691b4dbfc