This reverts commit e987606a.

Reason for revert: Speculatively reverting due to possible failure: https://ci.chromium.org/p/v8/builders/luci.v8.ci/Android%20Builder/8641

Original change's description:
> inspector: do not convert and store String16 for script source
> 
> We need script source for:
> - calculating hash to report as part of scriptParsed event,
> - reporting it as response on getScriptSource request,
> - searching inside as response on searchInContent request,
> - breakpoints hints.
> 
> In all cases there is no need to store source on inspector side.
> 
> R=​alph@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: Ice24ddc72cfff36fb9a2dff2d7c4543defe3f668
> Reviewed-on: https://chromium-review.googlesource.com/1182603
> Commit-Queue: Aleksey Kozyatinskiy <kozyatinskiy@chromium.org>
> Reviewed-by: Alexei Filippov <alph@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#55286}

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

Change-Id: I38d744dc811a5b747c1fcf27d88bdf770acf5c18
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/1184742Reviewed-by: Maya Lekova <mslekova@chromium.org>
Commit-Queue: Maya Lekova <mslekova@chromium.org>
Cr-Commit-Position: refs/heads/master@{#55290}