Devtools: Create layout editor experiment

Source/core/core.gypi

 {
     'includes': [
         'core_generated.gypi',
     ],
     'variables': {
         # Files for which bindings (.cpp and .h files) will be generated
         'core_idl_files': [
             'animation/KeyframeEffect.idl',
             'animation/EffectModel.idl',
             'animation/AnimationEffectReadOnly.idl',
@@ skipping 1675 matching lines @@
             'inspector/InspectorTimelineAgent.h',
             'inspector/InspectorTraceEvents.cpp',
             'inspector/InspectorTraceEvents.h',
             'inspector/InspectorTracingAgent.cpp',
             'inspector/InspectorTracingAgent.h',
             'inspector/InspectorWorkerAgent.cpp',
             'inspector/InspectorWorkerAgent.h',
             'inspector/InstrumentingAgents.h',
             'inspector/JSONParser.cpp',
             'inspector/JSONParser.h',
+            'inspector/LayoutEditor.cpp',
+            'inspector/LayoutEditor.h',
             'inspector/JavaScriptCallFrame.cpp',
             'inspector/JavaScriptCallFrame.h',
             'inspector/NetworkResourcesData.cpp',
             'inspector/NetworkResourcesData.h',
             'inspector/PageConsoleAgent.cpp',
             'inspector/PageConsoleAgent.h',
             'inspector/PageDebuggerAgent.cpp',
             'inspector/PageDebuggerAgent.h',
             'inspector/PageRuntimeAgent.cpp',
             'inspector/PageRuntimeAgent.h',
@@ skipping 2246 matching lines @@
             'style/OutlineValueTest.cpp',
             'style/SVGComputedStyleTest.cpp',
             'svg/UnsafeSVGAttributeSanitizationTest.cpp',
             'testing/PrivateScriptTestTest.cpp',
             'timing/MemoryInfoTest.cpp',
             'workers/WorkerThreadTest.cpp',
             'xml/parser/SharedBufferReaderTest.cpp',
         ],
     }
 }