Drive-by: make sure that Allocate node consistently take intptr
input as size (as opposed to sometimes intptr, sometimes int32).

Bug: v8:8984
Change-Id: Ida56b9788cd11b470cc866f1b7df71f03ef0075f
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1541037Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Commit-Queue: Jaroslav Sevcik <jarin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60551}