Per discussion on the public_webgl list -- see https://www.khronos.org/webgl/public-mailing-list/archives/1204/threads.html#00026 -- the Web IDL specification has been updated in a way that makes the following overloads for uniform1fv and related methods legal:
void uniform1fv(WebGLUniformLocation? location, Float32Array v);
void uniform1fv(WebGLUniformLocation? location, float v);
For the relevant diffs to Web IDL, see:
and possibly following edits.
The WebGL conformance tests need to be updated to verify that all of the other typed array types can be passed in to these functions, and that the float variant is matched during overload resolution.