Previous behavior diverged in ICs and Crankshaft. When storing to a Float32Array or Float64Array, the ICs treated undefined as zero while Crankshaft treated it as NaN. Now both ICs and Crankshaft treat it as NaN, which is consistent with the WebGL & ECMAScript spec.

R=mstarzinger@chromium.org

Review URL: https://chromiumcodereview.appspot.com/9402008

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@10714 ce2b1a6d-e550-0410-aec6-3dcde31c8c00