Avoid generating duplicate vmla instructions for vmul/vadd sequences where the
vmul has more than one use.
For example: function f(a, b, c) { return (a * b) + c + (a * b); }
Previously, this would produce a vmul for the subexpression (a * b), then vmla
for (a * b) + c, then vmla for (a * b) + [(a * b) + c].
Now it produces vmul, vadd, vadd, as expected.
BUG=
R=ulan@chromium.org
Review URL: https://codereview.chromium.org/323423003
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21899 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
736a17f8f4