The fix for bug 38145 broke the Chromium Win build because Microsoft's cmath doesn't define log2.
Suggested fix by zmo is to change log2(x) to log(x) / log(2).
Built and ran WebGL layout tests in Safari on Mac OS X.
Committed r60876: <http://trac.webkit.org/changeset/60876>
The fix didn't catch - now the log function calls are ambiguous between float, double or long double versions.
I added a 2nd quick fix in r60881 - adding explicit casts to double and double constants - which seems to have done the trick, at least as far as compilation goes (see http://trac.webkit.org/changeset/60881)