The spec for getParameter with the argument COMPRESSED_TEXTURE_FORMATS was recently changed to return a 0-length Uint32Array rather than null. WebKit's implementation needs to be changed to fix a conformance test failure.
The patch for https://bugs.webkit.org/show_bug.cgi?id=77066 covers this.
Fantastic, thanks. Closing this as a dup of the other.
*** This bug has been marked as a duplicate of bug 77066 ***