WTF::Vector: Fix primitive types identified as not safe to memcpy.
The culprit was the implementation of IsAssignable<> traits.
Specifically, "std::declval<T>() = X" is invalid if T is a primitive
type, because the assignment of primitives is not an overloaded
operator and the compilability of this statement for a primitive T is
different from that for a non-primitive T.
The fix is to simply change the left-hand side of the assignment to
"std::declval<T&>".
BUG=624642
Review-Url: https://codereview.chromium.org/2110183005
Cr-Commit-Position: refs/heads/master@{#403131}
2 files changed
