v8 opt: Copy arguments into new array rather than use [].slice
v8 opt: Copy arguments into new array rather than use [].slice

Calling Array.prototype.slice on the arguments object disables certain V8
optimizations. The Chrome Dev Tools profiler flags OO.Factory with the warning
"bad value context for arguments value". Using a simple array copy is just as
idiomatic and ought to work faster.

I didn't see a statistically significant improvement from this change, but I
plan on submitting these as I go down the list of warnings if the change needed
to make v8 happy doesn't compromise the readability of the code.

Some more details here: <https://github.com/jashkenas/coffeescript/issues/3274>

Bug: T74933
Change-Id: I4a0cf76f6a8d2e320088ae01ea26b5f05ca74105

wikimedia/oojs,wikimedia/oojs,iSCInc/oojs