Added conformance test for EXT_shader_texture_lod

Test originally authored by Vladimir Vukicevic. See https://bugzilla.mozilla.org/show_bug.cgi?id=965848
Merge pull request #568 from toji/shader_texture_lod_conformance

Added conformance test for EXT_shader_texture_lod
Add EXT_color_buffer_float proposal.
Merge pull request #569 from msc-hi/master

Add EXT_color_buffer_float proposal.
Add extra ANGLE test for scoped structures.

Because ANGLE internally uses a renaming scheme for scoped structures,
it's possible for the user to make certain structurse that conflict
with the internal scheme and cause link errors.

This bug only manifests in Firefox, not Chrome, because Chrome uses a
preliminary shader rewriting pass that hashes all variable names. It is
still possible to trigger from Chrome internal shaders and with
ANGLE as a standalone driver.
Merge pull request #572 from jamiemadill/scoped-structs-angle

Add extra ANGLE test for scoped structures.
Fixed relative links to CSS and image resouces.
Merge pull request #573 from kenrussell/latest-spec-links

Fixed relative links to CSS and image resouces.