Got WebGLRenderingContextBase to work with the "implements" syntax

Source/core/core.gypi

 {
     'variables': {
         # Files for which bindings (.cpp and .h files) will be generated
         'core_idl_files': [
             'animation/Animation.idl',
             'animation/AnimationPlayer.idl',
             'animation/TimedItem.idl',
             'animation/Timeline.idl',
             'animation/Timing.idl',
             'clipboard/DataTransfer.idl',
@@ skipping 229 matching lines @@
             'html/canvas/WebGLContextEvent.idl',
             'html/canvas/WebGLDebugRendererInfo.idl',
             'html/canvas/WebGLDebugShaders.idl',
             'html/canvas/WebGLDepthTexture.idl',
             'html/canvas/WebGLDrawBuffers.idl',
             'html/canvas/WebGLFramebuffer.idl',
             'html/canvas/WebGLLoseContext.idl',
             'html/canvas/WebGLProgram.idl',
             'html/canvas/WebGLRenderbuffer.idl',
             'html/canvas/WebGLRenderingContext.idl',
-            'html/canvas/WebGLRenderingContextBase.idl',
             'html/canvas/WebGLShader.idl',
             'html/canvas/WebGLShaderPrecisionFormat.idl',
             'html/canvas/WebGLTexture.idl',
             'html/canvas/WebGLUniformLocation.idl',
             'html/canvas/WebGLVertexArrayObjectOES.idl',
             'html/ime/InputMethodContext.idl',
             'html/track/TextTrack.idl',
             'html/track/TextTrackCue.idl',
             'html/track/TextTrackCueList.idl',
             'html/track/TextTrackList.idl',
@@ skipping 198 matching lines @@
             'dom/URLUtils.idl',
             'dom/URLUtilsReadOnly.idl',
             'events/EventListener.idl',
             'events/NavigatorEvents.idl',
             'frame/NavigatorID.idl',
             'frame/NavigatorOnLine.idl',
             'frame/WindowBase64.idl',
             'frame/WindowEventHandlers.idl',
             'frame/WindowTimers.idl',
             'html/canvas/CanvasPathMethods.idl',
+            'html/canvas/WebGLRenderingContextBase.idl',
             'page/WindowPagePopup.idl',
             'svg/SVGDocument.idl',
             'svg/SVGFilterPrimitiveStandardAttributes.idl',
             'svg/SVGFitToViewBox.idl',
             'svg/SVGTests.idl',
             'svg/SVGURIReference.idl',
             'svg/SVGZoomAndPan.idl',
             'workers/AbstractWorker.idl',
             'xml/DocumentXPathEvaluator.idl',
         ],
@@ skipping 2844 matching lines @@
             'html/track/vtt/BufferedLineReaderTest.cpp',
             'html/track/vtt/VTTScannerTest.cpp',
             'rendering/RenderOverflowTest.cpp',
             'rendering/shapes/BoxShapeTest.cpp',
             'testing/UnitTestHelpers.cpp',
             'testing/UnitTestHelpers.h',
             'xml/parser/SharedBufferReaderTest.cpp',
         ],
     }
 }