Even after https://codereview.chromium.org/2371963002 we still did not
always store a Smi into the JSTypedArray::length field, the runtime
function %TypedArrayInitializeFromArrayLike was still storing whatever
it got from the JavaScript code, which is highly dependent on internal
decisions of the ICs and the representation selection in the optimizing
compilers, so that's pretty fragile.
R=verwaest@chromium.org
BUG=chromium:650933
Review-Url: https://codereview.chromium.org/2377943002
Cr-Commit-Position: refs/heads/master@{#39802}
