Added draft extension proposal.
Per https://code.google.com/p/chromium/issues/detail?id=427065 and modeled after https://www.opengl.org/registry/specs/KHR/robust_buffer_access_behavior.txt , relax the bounds checking requirements on array accesses.  This should allow D3D to avoid unnecessary bounds checks.
Generalize the possible scenarios to KHR_robust_buffer_access_behavior's semantics.
Added draft extension proposal.
Updated proposal
Rewording
Merge pull request #787 from orglofch/subscribe-unform-proposal

Add draft extension proposal for WEBGL_subscribe_uniform.