calling 'reshape(0,0)' when destroying webgl context

This releases the textures attached to context fbo faster, without waiting for GC.
These textures make up for the most of gfx memory used, and when opening different apps
quickly we may run out of gfx memory before GC kicks in.

Author: tomasz-karczewski-red

Source/WebCore/html/canvas/WebGLRenderingContextBase.cpp

@@ -1305,6 +1305,8 @@ void WebGLRenderingContextBase::destroyGraphicsContextGL()
     removeActivityStateChangeObserver();
 
     if (m_context) {
+        // first release the big textures allocated for the FBOs
+        m_context->reshape(0,0);
         m_context->setClient(nullptr);
         m_context = nullptr;
         removeActiveContext(*this);