Fix some incorrect extension queries on OpenGL part.
GL_MAX_FRAMEBUFFER_WIDTH should be checked by
GL_ARB_framebuffer_no_attachments.
GL_MAX_COMPUTE_SHADER_STORAGE_BLOCKS should be checked by
GL_ARB_shader_storage_buffer_object and GL_ARB_compute_shader.
Also do code refactoring for query GL_MAX_FRAGMENT_UNIFORM_VECTORS,
GL_MAX_VERTEX_UNIFORM_BLOCKS and GL_MAX_FRAGMENT_UNIFORM_BLOCKS.

BUG=angleproject:2256

Change-Id: Iea2471363551019dfeb97f224eea808de19914ab
Reviewed-on: https://chromium-review.googlesource.com/781239
Commit-Queue: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>