Move detachGLFunctor call before hardware teardown.

By not detaching the GL functor until after the teardown, we ran the
risk of stray draw calls occurring that could potentially reinitialize
the hardware renderer, causing the SharedRendererState destructor to
DCHECK.

BUG=

Review URL: https://codereview.chromium.org/920083002

Cr-Commit-Position: refs/heads/master@{#316222}

android_webview/java/src/org/chromium/android_webview/AwContents.java

@@ -2209,6 +2209,7 @@ public class AwContents implements SmartClipProvider {
     // draw functor destruction.
     @CalledByNative
     private void invalidateOnFunctorDestroy() {
+        mNativeGLDelegate.detachGLFunctor();
         mContainerView.invalidate();
     }
 
@@ -2566,7 +2567,6 @@ public class AwContents implements SmartClipProvider {
             }
 
             mScrollAccessibilityHelper.removePostedCallbacks();
-            mNativeGLDelegate.detachGLFunctor();
         }
 
         @Override