Add keys(), values() and entries() methods on iterable<> interfaces

Source/core/core.gypi

 {
     'includes': [
         'core_generated.gypi',
     ],
     'variables': {
         # Files for which bindings (.cpp and .h files) will be generated
         'core_idl_files': [
             'animation/Animation.idl',
             'animation/AnimationEffect.idl',
             'animation/AnimationNode.idl',
@@ skipping 2153 matching lines @@
             'dom/GlobalEventHandlers.h',
             'dom/IconURL.cpp',
             'dom/IconURL.h',
             'dom/IdTargetObserver.cpp',
             'dom/IdTargetObserver.h',
             'dom/IdTargetObserverRegistry.cpp',
             'dom/IdTargetObserverRegistry.h',
             'dom/IgnoreDestructiveWriteCountIncrementer.h',
             'dom/IncrementLoadEventDelayCount.cpp',
             'dom/IncrementLoadEventDelayCount.h',
+            'dom/Iterable.h',
             'dom/Iterator.h',
             'dom/LiveNodeList.cpp',
             'dom/LiveNodeList.h',
             'dom/LiveNodeListBase.cpp',
             'dom/LiveNodeListBase.h',
             'dom/MainThreadTaskRunner.cpp',
             'dom/MainThreadTaskRunner.h',
             'dom/MessageChannel.cpp',
             'dom/MessageChannel.h',
             'dom/MessagePort.cpp',
@@ skipping 1551 matching lines @@
             'rendering/style/RenderStyleTest.cpp',
             'rendering/style/SVGRenderStyleTest.cpp',
             'streams/ReadableStreamTest.cpp',
             'testing/PrivateScriptTestTest.cpp',
             'testing/UnitTestHelpers.cpp',
             'testing/UnitTestHelpers.h',
             'xml/parser/SharedBufferReaderTest.cpp',
         ],
     }
 }