remote MapBuffer-related constants from test
Mention MapBufferRange in the list of differences from OpenGL ES 3.0
add IMPLEMENTATION_COLOR_* constants to the enums test
Merge pull request #697 from bjacob/webgl2-tests-fixes

Make constants-and-properties-2.html passable (take 2)
add vertexAttribIPointer
Merge pull request #698 from bjacob/vertexAttribIPointer

add vertexAttribIPointer to test