Verify if component values are set correct

GLSL constructors : Added code to verify if component values are set
correct by constructor expression.
Added text to all new interfaces except WebGLSync, which I'm not terribly familiar with
Made the latest spec landing page slightly more useful
Added desriptions of VertexArray functions
Added conformance test for EXT_blend_minmax
Merge pull request #567 from toji/blend_minmax_conformance

Added conformance test for EXT_blend_minmax
Shorter comparison fp component validity check

More compact comparison for floating point component validity check by
using abs() instead of separate positive and negative comparison
encapsulates -> encapsulate
Merge pull request #565 from toji/webgl2-spec-interfaces

Added text to all new WebGL2 interfaces except WebGLSync
Fixed title
Merge pull request #566 from toji/spec-landing

Made the latest spec landing page slightly more useful
Merge pull request #535 from TiborsHub/master

Verify if component values are set correct
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.