Implement Resume and Reload Without Breaks feature

Review URL: https://chromiumcodereview.appspot.com/20566002

git-svn-id: svn://svn.chromium.org/blink/trunk@157313 bbb929c8-8fbe-4397-9dbb-9b2b20218538
REGRESSION(r156139) Fix placeholder handling at end of editable root

This patch changes placeholder handling at end of editable root in DeleteSelectionCommand::doApply() to insert placeholder in allow below conditions are satisfied after selection deleted:
 - there is a placeholder.
 - there is line break before deleted selection.
 - line break wasn't at end of deleted selection.

editing/deleting/delete-character-002.html
 - Test cases for TEXTAREA

editing/deleting/delete-character-003.html
 - Test cases for HTML editing

editing/deleting/delete-character-004.html
 - Moved a test case to delete-character-003.html

BUG=264986
TEST=LayoutTests/editing/deleting/delete-character-002.html, LayoutTests/editing/deleting/delete-character-003.html

Review URL: https://chromiumcodereview.appspot.com/23857002

git-svn-id: svn://svn.chromium.org/blink/trunk@157314 bbb929c8-8fbe-4397-9dbb-9b2b20218538
[blink]: Annotate StringImpl::createStatic leak for LeakSanitizer.

Adding the annotation WTF_ANNOTATE_SCOPED_MEMORY_LEAK in StringImpl::createStatic to ensure leak sanitizer doesn't report this as a leak.
This patch just handles Leak Sanitizer only. The changes for Heap Checker will be done in a follow up patch.

BUG=268258
TEST=Running content_unittests with Leak Sanitizer enabled.
Output of Leak Sanitizer before the fix: http://pastebin.com/niDgRNAQ
Output of Leak Sanitizer after the fix: http://pastebin.com/v6hF43Lj

Review URL: https://chromiumcodereview.appspot.com/23901002

git-svn-id: svn://svn.chromium.org/blink/trunk@157315 bbb929c8-8fbe-4397-9dbb-9b2b20218538