Remove the Promises old implementation.

Source/core/core.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',
             'animation/AnimationTimeline.idl',
             'animation/TimedItem.idl',
             'animation/Timing.idl',
@@ skipping 56 matching lines @@
             'dom/MessagePort.idl',
             'dom/MutationObserver.idl',
             'dom/MutationRecord.idl',
             'dom/NamedNodeMap.idl',
             'dom/Node.idl',
             'dom/NodeFilter.idl',
             'dom/NodeIterator.idl',
             'dom/NodeList.idl',
             'dom/Notation.idl',
             'dom/ProcessingInstruction.idl',
-            'dom/Promise.idl',
             'dom/Range.idl',
             'dom/RequestAnimationFrameCallback.idl',
             'dom/StringCallback.idl',
             'dom/Text.idl',
             'dom/Touch.idl',
             'dom/TouchList.idl',
             'dom/TreeWalker.idl',
             'dom/URL.idl',
             'dom/XMLDocument.idl',
             'dom/shadow/ShadowRoot.idl',
@@ skipping 1968 matching lines @@
             'dom/Notation.h',
             'dom/ParentNode.h',
             'dom/PendingScript.cpp',
             'dom/Position.cpp',
             'dom/PositionIterator.cpp',
             'dom/PositionIterator.h',
             'dom/PresentationAttributeStyle.cpp',
             'dom/PresentationAttributeStyle.h',
             'dom/ProcessingInstruction.cpp',
             'dom/ProcessingInstruction.h',
-            'dom/Promise.h',
             'dom/PseudoElement.cpp',
             'dom/QualifiedName.cpp',
             'dom/Range.cpp',
             'dom/RawDataDocumentParser.h',
             'dom/RenderTreeBuilder.cpp',
             'dom/RenderTreeBuilder.h',
             'dom/RequestAnimationFrameCallback.h',
             'dom/SandboxFlags.cpp',
             'dom/SandboxFlags.h',
             'dom/ScriptForbiddenScope.cpp',
@@ skipping 1310 matching lines @@
             'html/track/vtt/VTTScannerTest.cpp',
             'loader/MixedContentCheckerTest.cpp',
             'rendering/RenderOverflowTest.cpp',
             'rendering/shapes/BoxShapeTest.cpp',
             'testing/UnitTestHelpers.cpp',
             'testing/UnitTestHelpers.h',
             'xml/parser/SharedBufferReaderTest.cpp',
         ],
     }
 }