This reverts commit 1b3b808a.

Reason for revert: Speculatively reverting because of https://ci.chromium.org/p/v8/builders/luci.v8.ci/V8-Blink%20Linux%2064%20(dbg)/13264

Original change's description:
> inspector: find magic comment using V8 scanner
> 
> Inspector tries to provide sourceURL and sourceMappingURL for scripts
> with parser errors. Without this CL we convert source of each script
> to inspector string and search for magic comment there. Some web sites
> use pattern when they get some data from network and constantly try to
> parse this data as JSON, in this case we do a lot of useless work.
> 
> So we can parse magic comments on V8 side only for compilation errors
> (excluding parse JSON errors), to do it we can reuse scanner by running
> it on each potential comment.
> 
> R=​alph@chromium.org,verwaest@chromium.org,yangguo@chromium.org
> 
> Bug: chromium:873865,v8:7731
> Cq-Include-Trybots: luci.chromium.try:linux_chromium_headless_rel;master.tryserver.blink:linux_trusty_blink_rel
> Change-Id: I77c270fd0e95cd7b2c9ee4b7f72ef344bc1fa104
> Reviewed-on: https://chromium-review.googlesource.com/1182446
> Reviewed-by: Toon Verwaest <verwaest@chromium.org>
> Reviewed-by: Alexei Filippov <alph@chromium.org>
> Commit-Queue: Aleksey Kozyatinskiy <kozyatinskiy@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#55280}

TBR=alph@chromium.org,yangguo@chromium.org,kozyatinskiy@chromium.org,verwaest@chromium.org

Change-Id: I60ab243107d5fcce100064232d0e278a51f38db9
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: chromium:873865, v8:7731
Cq-Include-Trybots: luci.chromium.try:linux_chromium_headless_rel;master.tryserver.blink:linux_trusty_blink_rel
Reviewed-on: https://chromium-review.googlesource.com/1184921Reviewed-by: Maya Lekova <mslekova@chromium.org>
Commit-Queue: Maya Lekova <mslekova@chromium.org>
Cr-Commit-Position: refs/heads/master@{#55300}