Bind Window focus ability to the ExecutionContext instead of the process.

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 2170 matching lines @@
             'dom/QualifiedName.cpp',
             'dom/Range.cpp',
             'dom/RawDataDocumentParser.h',
             'dom/RemoteSecurityContext.cpp',
             'dom/RemoteSecurityContext.h',
             'dom/RenderTreeBuilder.cpp',
             'dom/RenderTreeBuilder.h',
             'dom/RequestAnimationFrameCallback.h',
             'dom/SandboxFlags.cpp',
             'dom/SandboxFlags.h',
+            'dom/ScopedWindowFocusAllowedIndicator.cpp',
+            'dom/ScopedWindowFocusAllowedIndicator.h',
             'dom/ScriptLoader.cpp',
             'dom/ScriptLoader.h',
             'dom/ScriptRunner.cpp',
             'dom/ScriptRunner.h',
             'dom/ScriptableDocumentParser.cpp',
             'dom/ScriptableDocumentParser.h',
             'dom/ScriptedAnimationController.cpp',
             'dom/ScriptedAnimationController.h',
             'dom/SecurityContext.cpp',
             'dom/SecurityContext.h',
@@ skipping 1396 matching lines @@
             'rendering/style/OutlineValueTest.cpp',
             'rendering/style/RenderStyleTest.cpp',
             'streams/ReadableStreamTest.cpp',
             'testing/PrivateScriptTestTest.cpp',
             'testing/UnitTestHelpers.cpp',
             'testing/UnitTestHelpers.h',
             'xml/parser/SharedBufferReaderTest.cpp',
         ],
     }
 }