Make sure view port and frame buffer are set to the correct values
before calling GL functor (WebView) draw.
Improve correctness for stencil clip by doing a second flush that
guarantees the stencil clear will be executed after draw commands.
Bug: 79619253
Test: XFINITY Connect app draws correctly
Change-Id: Ieb3d0d70caf0469b6393e6287f8529cd86519301