We have roughly a 7x (5x on ia32) ratio between bytecode and sparkplug
code. Using this number to preallocate the buffer for the emitted code
we can avoid a few copies for larger functions.

Drive-by-fix: Make sure EnsureSpace is marked V8_INLINE

Bug: v8:11420
Change-Id: I6ec48717d2e030c6118c59f5cdc286c952ec2843
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2835732
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74085}