https://bugs.webkit.org/show_bug.cgi?id=97825

Reviewed by Ryosuke Niwa.

Source/WebCore:

Adds a DocumentOrderedMap to TreeScope that allows accessibility to
quickly map from an id to the label for that id. This speeds up
AccessibilityNode::labelForElement, which was a bottleneck in Chromium
when accessibility was on.

Tests: accessibility/title-ui-element-correctness.html
       perf/accessibility-title-ui-element.html

* accessibility/AccessibilityNodeObject.cpp:
(WebCore::AccessibilityNodeObject::labelForElement):
* dom/DocumentOrderedMap.cpp:
(WebCore::keyMatchesLabelForAttribute):
(WebCore):
(WebCore::DocumentOrderedMap::get):
(WebCore::DocumentOrderedMap::getElementByLabelForAttribute):
* dom/DocumentOrderedMap.h:
(DocumentOrderedMap):
* dom/Element.cpp:
(WebCore::Element::insertedInto):
(WebCore::Element::removedFrom):
(WebCore::Element::updateLabel):
(WebCore):
(WebCore::Element::willModifyAttribute):
* dom/Element.h:
(Element):
* dom/TreeScope.cpp:
(WebCore::TreeScope::TreeScope):
(WebCore::TreeScope::destroyTreeScopeData):
(WebCore::TreeScope::addLabel):
(WebCore):
(WebCore::TreeScope::removeLabel):
(WebCore::TreeScope::labelElementForId):
* dom/TreeScope.h:
(WebCore):
(TreeScope):
(WebCore::TreeScope::shouldCacheLabelsByForAttribute):

Tools:

Implement titleUIElement in the chromium port of DRT, and
fix getAccessibleElementById so that it ensures the backing store
is up-to-date.

* DumpRenderTree/chromium/TestRunner/AccessibilityControllerChromium.cpp:
(AccessibilityController::getAccessibleElementById):
* DumpRenderTree/chromium/TestRunner/AccessibilityUIElementChromium.cpp:
(AccessibilityUIElement::titleUIElementCallback):

LayoutTests:

Adds two new tests for titleUIElement that run on both Mac and
Chromium. One tests correctness, the other tests speed.

Fixes one test so that it passes on Chromium.
Enables other tests that now pass on Chromium.

* accessibility/secure-textfield-title-ui.html:
* accessibility/title-ui-element-correctness-expected.txt: Added.
* accessibility/title-ui-element-correctness.html: Added.
* perf/accessibility-title-ui-element-expected.txt: Added.
* perf/accessibility-title-ui-element.html: Added.
* platform/chromium/TestExpectations:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@131871 268f45cc-cd09-0410-ab3c-d52691b4dbfc