Reland of Change assert to release assert for WTF::double_conversion::Vector...

Reland of Change assert to release assert for WTF::double_conversion::Vector to prevent OOB memory access. (patchset #1 id:1 of https://codereview.chromium.org/1694093002/ )

Reason for revert:
This revert was not the culprit CL. Reverting the revert.

Original issue's description:
> Revert of Change assert to release assert for WTF::double_conversion::Vector to prevent OOB memory access. (patchset #2 id:20001 of https://codereview.chromium.org/1677363002/ )
>
> Reason for revert:
> Perf failures. Speculative revert to see if it fixes.
>
> BUG=586581,574802
>
> Original issue's description:
> > Change assert to release assert for WTF::double_conversion::Vector to prevent OOB memory access.
> >
> > R=inferno@chromium.org, mbarbella@chromium.org, ochang@chromium.org, tkent@chromium.org
> > BUG=574802
> >
> > Committed: https://crrev.com/ad618c3357e189fb685ea88fe4b8b25ac34f2c75
> > Cr-Commit-Position: refs/heads/master@{#374424}
>
> TBR=mbarbella@chromium.org,ochang@chromium.org,tkent@chromium.org,mmoroz@chromium.org
> # Not skipping CQ checks because original CL landed more than 1 days ago.
> BUG=574802
>
> Committed: https://crrev.com/64cb1f5327522142c658100746f34f8a012a45fa
> Cr-Commit-Position: refs/heads/master@{#375389}

TBR=mbarbella@chromium.org,ochang@chromium.org,tkent@chromium.org,mmoroz@chromium.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=586581,574802

Review URL: https://codereview.chromium.org/1708703003

Cr-Commit-Position: refs/heads/master@{#376043}

third_party/WebKit/Source/wtf/dtoa/utils.h

@@ -163,9 +163,9 @@ namespace double_conversion {
         // Returns the pointer to the start of the data in the vector.
         T* start() const { return start_; }
 
-        // Access individual vector elements - checks bounds in debug mode.
+        // Access individual vector elements.
         T& operator[](int index) const {
-            ASSERT(0 <= index && index < length_);
+            RELEASE_ASSERT(0 <= index && index < length_);
             return start_[index];
         }