vcl: Some fixes to the OpenGL impl

Change-Id: I58466142e0a47beb892e10113c1bc34d5ac3abcd
vcl: Add methods to get size of OpenGLSalGraphicsImpl

Change-Id: I7eecbc236db12fb9453384985245eb5ca781e0f5
vcl: Update OpenGL context before drawing

Change-Id: I7575881d8d9a2026a74692ca562a340231d946bd
vcl: Add OpenGLSalBitmap implementation

Change-Id: I0deebaedf6fe5b23f50a448eea0d5d9e99ebd391
vcl: Remove the extra colon at the end of shader

Change-Id: I0a1a2346176a9f2f4d62ca80a9485d720b522cef