Patch is at https://crrev.com/2790463002

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/54702b16778aa3319f93a32d3ffdc4aef1c9a831

commit 54702b16778aa3319f93a32d3ffdc4aef1c9a831
Author: cblume <cblume@chromium.org>
Date: Thu Mar 30 19:33:00 2017

Fix WTF::makeUnique for arrays

base::makeUnique and std::make_unique support allocating arrays with the
syntax base::makeUnique<char[]>(20).

WTF::makeUnique calls WTF::IsGarbageCollectedType<T> to make sure it
isn't attempting to makeUnique on a GC type. But that requires T be a
complete type, and char[] isn't.

R=esprehn@chromium.org
BUG= 706715 

Review-Url: https://codereview.chromium.org/2790463002
Cr-Commit-Position: refs/heads/master@{#460850}

[modify] https://crrev.com/54702b16778aa3319f93a32d3ffdc4aef1c9a831/third_party/WebKit/Source/platform/BUILD.gn
[modify] https://crrev.com/54702b16778aa3319f93a32d3ffdc4aef1c9a831/third_party/WebKit/Source/platform/wtf/PtrUtil.h
[add] https://crrev.com/54702b16778aa3319f93a32d3ffdc4aef1c9a831/third_party/WebKit/Source/platform/wtf/PtrUtilTest.cpp