This retrieves script name directly from StackFrameBase, bypassing
building of StackFrameInfo if one hasn't already been initialized,
thus avoiding computation of expensive properties that are not required.
This matches current behavior of GetScriptNameOrSourceURL() and is a
workaround until a dedicated API is available.

This is necessary to switch AdTagging over from using
GetScriptNameOrSourceURL() to GetScriptName(), to ensure that scripts
with source urls are tagged appropriately. (See crrev.com/c/2551259.)

Bug: chromium:1127391
Change-Id: I6eb145b88c26deb1a088f038b0f8b377bc8fe3ab
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2550504Reviewed-by: Simon Zünd <szuend@chromium.org>
Commit-Queue: Alex Turner <alexmt@chromium.org>
Cr-Commit-Position: refs/heads/master@{#71318}