Many changes have been made to the WebGL specification for the planned version 1.0.2 in order to make the specification correct with respect to nullable arguments and return types. The conformance tests need to be updated to take these changes in to account.
The scope of these changes isn't completely clear. It may be as simple as adding a few more tests for entry points which can accept null where they could not before. bufferSubData, texImage2D (certain overloads) and texSubImage2D are a few methods needing to be updated -- but this is not an exhaustive list.