Removed arbitrary 4096 size limit on WebGL canvas backbuffers

Source/platform/graphics/gpu/DrawingBuffer.h

Index: Source/platform/graphics/gpu/DrawingBuffer.h
diff --git a/Source/platform/graphics/gpu/DrawingBuffer.h b/Source/platform/graphics/gpu/DrawingBuffer.h
index d2531168184b3acb2b53f3d106097debe43f2abf..99119f6918dae0b8ea3ecf4b0c32cfb2461a47d0 100644
--- a/Source/platform/graphics/gpu/DrawingBuffer.h
+++ b/Source/platform/graphics/gpu/DrawingBuffer.h
@@ -185,7 +185,7 @@ private:
     void createSecondaryBuffers();
     bool resizeFramebuffer(const IntSize&);
     bool resizeMultisampleFramebuffer(const IntSize&);
-    void resizeDepthStencil(const IntSize&);
+    bool resizeDepthStencil(const IntSize&);
 
     // Bind to the m_framebufferBinding if it's not 0. Otherwise, bind to the default FBO.
     void restoreFramebufferBinding();
@@ -219,7 +219,7 @@ private:
     // By default, alignment is 4, the OpenGL default setting.
     void texImage2DResourceSafe(GLenum target, GLint level, GLenum internalformat, GLsizei width, GLsizei height, GLint border, GLenum format, GLenum type, GLint alignment = 4);
     // Allocate buffer storage to be sent to compositor using either texImage2D or CHROMIUM_image based on available support.
-    void allocateTextureMemory(TextureInfo*, const IntSize&);
+    bool allocateTextureMemory(TextureInfo*, const IntSize&);
     void deleteChromiumImageForTexture(TextureInfo*);
 
     PreserveDrawingBuffer m_preserveDrawingBuffer;