Fix ES2 composition on some devices

- turns out fragment shaders don't have default precision by default
- GLES 1.x extensions that became core in GLES 2.0 don't always work
  as extensions in GLES 2.0 (!)

Bug: 8679321
Change-Id: I5a4a93e158247910399325a965af5d2e3bbece9b