DevTools: [CSS] fix style ranges updating

DevTools: [CSS] fix style ranges updating

DevTools CSSOM objects (like WebInspector.CSSRule,
WebInspector.CSSStyleDeclaration) are addressed by their ranges in source code
(aka "source ranges"). Whenever some property gets changed, all the
source ranges that lay afterwards in the same stylesheet have to be updated.

Unfortunately, there was a typo in this bookkeeping operation. This patch
fixes it and covers with a testcase.

BUG=390300
R=apavlov, vsevik

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=177401

[lushnikov, 2014-07-02 14:31:11]

Ptal!

[vsevik, 2014-07-02 15:01:00]

lgtm

[commit-bot: I haz the power, 2014-07-02 15:02:13]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/lushnikov@chromium.org/368013002/1

[commit-bot: I haz the power, 2014-07-02 15:54:17]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  win_blink_rel on tryserver.blink
(http://build.chromium.org/p/tryserver.blink/builders/win_blink_rel/builds/15079)

[commit-bot: I haz the power, 2014-07-02 17:06:03]

Change committed as 177401