Restore untrusted glStencilMask value on resume after functor

Fixes an issue where the stencil buffer is corrupted
(used in overdraw debugging, path clipping) when used in
conjunction with a HW accelerated WebView.

bug:15023700
bug:16465551

Change-Id: If201b503931380f7107a34e9a9a2f877a50f72b1
[Bitmap] Add null pointer protection in Bitmap_sameAs()

Symptom: SkBitmap::getAddr(int, int) may return NULL due to unrecognized config
(ex: kRLE_Index8_Config). This will cause memcmp method to crash. Since bm0 and
bm1 both have pixel data() (have passed NULL == getPixels() check), those 2
bitmaps should be valid (only unrecognized), we return JNI_FALSE to warn user
those 2 unrecognized config bitmaps may be different.

Change-Id: I6970c27de412110a3035d0a783112c4cd3ebc35b
[HWUI] Fix invisible views are still shown in popup window

Symptom: Invisible views are still shown in popup window

Root Cause: glClear isn't called if there is no draw command

Solution: Even if there is no draw command, it still calls glClear
          by startFrame().

Reproduce steps: App set one view in a popup window to invisible,
                 it will be still visible.

Change-Id: I36bc7b752434ad388fbb80ea63341ac778f48d35