DevTools: make heap profiler work when there are nodes retained by weak references only

In some cases we get snapshots that contain nodes retained by weak references only (most likely due to a bug in v8, see crbug.com/426809), this breaks algorithm that caclculates dominators and leads to incorrect total heap snapshot size to be reported. This patch makes root dominator of such nodes. This way retained size of such orphan nodes is estimated correctly. The orphan node ids are still printed into console.

Shortcut references are considered the same way as weak refs from the dominance/retained size point of view.

BUG=426389

Review URL: https://codereview.chromium.org/679683002

git-svn-id: svn://svn.chromium.org/blink/trunk@184450 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Revert of DevTools: [CodeMirrro] defer autocomplete controller initialization (patchset #2 id:20001 of https://codereview.chromium.org/670163002/)

Reason for revert:
Breaks autocomplete (only ctrl+space works)

Original issue's description:
> DevTools: [CodeMirrro] defer autocomplete controller initialization
> 
> Autocompletion controller intialization makes almost half of the time
> of SourceFrame initialization.
> 
> In order to render editor as fast as possible, this patch defers
> autocompletion initialization until the first need.
> 
> BUG=425550
> R=vsevik
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=184263

TBR=lushnikov@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=425550

Review URL: https://codereview.chromium.org/676393003

git-svn-id: svn://svn.chromium.org/blink/trunk@184451 bbb929c8-8fbe-4397-9dbb-9b2b20218538