Support Promises event-based instrumentation on backend.

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/AnimationPlayer.idl',
@@ skipping 1311 matching lines @@
             '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',
+            'inspector/PromiseTracker.cpp',
+            'inspector/PromiseTracker.h',
             'inspector/ScriptArguments.cpp',
             'inspector/ScriptArguments.h',
             'inspector/ScriptAsyncCallStack.cpp',
             'inspector/ScriptAsyncCallStack.h',
             'inspector/ScriptCallFrame.cpp',
             'inspector/ScriptCallFrame.h',
             'inspector/ScriptCallStack.cpp',
             'inspector/ScriptCallStack.h',
             'inspector/ScriptGCEventListener.h',
             'inspector/ScriptProfile.cpp',
@@ skipping 2118 matching lines @@
             'rendering/shapes/BoxShapeTest.cpp',
             'rendering/style/OutlineValueTest.cpp',
             'testing/PrivateScriptTestTest.cpp',
             'streams/ReadableStreamTest.cpp',
             'testing/UnitTestHelpers.cpp',
             'testing/UnitTestHelpers.h',
             'xml/parser/SharedBufferReaderTest.cpp',
         ],
     }
 }