IDL: make optional arguments (without default) explicit sometimes

Source/bindings/core/v8/custom/V8CanvasRenderingContext2DCustom.cpp

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 60 matching lines @@
     v8SetReturnValue(info, toV8Object(impl->strokeStyle(), info.Holder(), info.GetIsolate()));
 }
 
 void V8CanvasRenderingContext2D::strokeStyleAttributeSetterCustom(v8::Local<v8::Value> value, const v8::PropertyCallbackInfo<void>& info)
 {
     CanvasRenderingContext2D* impl = V8CanvasRenderingContext2D::toNative(info.Holder());
     if (RefPtrWillBeRawPtr<CanvasStyle> canvasStyle = toCanvasStyle(value, info.GetIsolate())) {
         impl->setStrokeStyle(canvasStyle);
     } else {
         TOSTRING_VOID(V8StringResource<>, colorString, value);
-        impl->setStrokeColor(colorString);
+        impl->setStrokeColor(colorString, makeOptionalMissing<float>());
     }
 }
 
 void V8CanvasRenderingContext2D::fillStyleAttributeGetterCustom(const v8::PropertyCallbackInfo<v8::Value>& info)
 {
     CanvasRenderingContext2D* impl = V8CanvasRenderingContext2D::toNative(info.Holder());
     v8SetReturnValue(info, toV8Object(impl->fillStyle(), info.Holder(), info.GetIsolate()));
 }
 
 void V8CanvasRenderingContext2D::fillStyleAttributeSetterCustom(v8::Local<v8::Value> value, const v8::PropertyCallbackInfo<void>& info)
 {
     CanvasRenderingContext2D* impl = V8CanvasRenderingContext2D::toNative(info.Holder());
     if (RefPtrWillBeRawPtr<CanvasStyle> canvasStyle = toCanvasStyle(value, info.GetIsolate())) {
         impl->setFillStyle(canvasStyle);
     } else {
         TOSTRING_VOID(V8StringResource<>, colorString, value);
-        impl->setFillColor(colorString);
+        impl->setFillColor(colorString, makeOptionalMissing<float>());
     }
 }
 
 } // namespace blink