According to the latest spec changes the WasmToJS wrapper and the
JSToWasm wrapper through a TypeError if the signature of the wrapper
contains a I64 parameter or return value. Originally the TypeError was
thrown when the parameter or return value was converted to or from JS.

In addition I removed all special handling of I64 parameters and return
values in the wrappers which was already dead code.

R=titzer@chromium.org

Review-Url: https://codereview.chromium.org/2626853003
Cr-Commit-Position: refs/heads/master@{#42238}