Don't access RT when disabling scissor.

src/gpu/gl/GrGpuGL.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #include "GrGpuGL.h"
 #include "GrGLStencilBuffer.h"
@@ skipping 1253 matching lines @@
         return NULL;
     }
 }
 
 GrPath* GrGpuGL::onCreatePath(const SkPath& inPath) {
     SkASSERT(this->caps()->pathStencilingSupport());
     return SkNEW_ARGS(GrGLPath, (this, inPath));
 }
 
 void GrGpuGL::flushScissor() {
-    const GrDrawState& drawState = this->getDrawState();
-    const GrGLRenderTarget* rt =
-        static_cast<const GrGLRenderTarget*>(drawState.getRenderTarget());
+    if (fScissorState.fEnabled) {
+        // Only access the RT if scissoring is being enabled. We can call this before performing
+        // a glBitframebuffer for a surface->surface copy, which requires no RT to be bound to the
+        // GrDrawState.
+        const GrDrawState& drawState = this->getDrawState();
+        const GrGLRenderTarget* rt =
+            static_cast<const GrGLRenderTarget*>(drawState.getRenderTarget());
 
-    SkASSERT(NULL != rt);
-    const GrGLIRect& vp = rt->getViewport();
-
-    if (fScissorState.fEnabled) {
+        SkASSERT(NULL != rt);
+        const GrGLIRect& vp = rt->getViewport();
         GrGLIRect scissor;
         scissor.setRelativeTo(vp,
                               fScissorState.fRect.fLeft,
                               fScissorState.fRect.fTop,
                               fScissorState.fRect.width(),
                               fScissorState.fRect.height(),
                               rt->origin());
         // if the scissor fully contains the viewport then we fall through and
         // disable the scissor test.
         if (!scissor.contains(vp)) {
@@ skipping 1296 matching lines @@
             this->setVertexArrayID(gpu, 0);
         }
         int attrCount = gpu->glCaps().maxVertexAttributes();
         if (fDefaultVertexArrayAttribState.count() != attrCount) {
             fDefaultVertexArrayAttribState.resize(attrCount);
         }
         attribState = &fDefaultVertexArrayAttribState;
     }
     return attribState;
 }