Remove platform-specific Float64Pow implementations and utils Pow in
favor of a base::ieee754::pow implementation.

This unifies the implementation of pow for the compiler, wasm, and
runtime.

Bug: v8:5848, v8:5086
Change-Id: I968a08cef6a6d49350aa79185b2c6fb856d15f23
Reviewed-on: https://chromium-review.googlesource.com/c/1403018
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Georg Neis <neis@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59229}