gpu: Remove WebGraphicsContext3D::makeContextCurrent() in Blink

Source/platform/graphics/test/MockWebGraphicsContext3D.h

Index: Source/platform/graphics/test/MockWebGraphicsContext3D.h
diff --git a/Source/platform/graphics/test/MockWebGraphicsContext3D.h b/Source/platform/graphics/test/MockWebGraphicsContext3D.h
index 6e93a24496e96757401b9739d0c8c6325ba40011..d41a81013b5a527cef1f69270a9b7ed7f83cb690 100644
--- a/Source/platform/graphics/test/MockWebGraphicsContext3D.h
+++ b/Source/platform/graphics/test/MockWebGraphicsContext3D.h
@@ -41,8 +41,6 @@ public:
     {
     }
 
-    virtual bool makeContextCurrent() { return true; }
-
     virtual void prepareTexture() { }
 
     virtual void postSubBufferCHROMIUM(int x, int y, int width, int height) { }