Re-land: Adding PreRole in blink side to expose HTML pre tag with correct MSAA+IA2.

It was reverted due to bug 426608; the fix was landed on the Chromium side.

Original review url: https://codereview.chromium.org/671003002

BUG=426608,426053
TBR=leviw

Review URL: https://codereview.chromium.org/663233004

git-svn-id: svn://svn.chromium.org/blink/trunk@184337 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/core/accessibility/AXObject.h

@@ -132,6 +132,7 @@ enum AccessibilityRole {
     OutlineRole,
     ParagraphRole,
     PopUpButtonRole,
+    PreRole,
     PresentationalRole,
     ProgressIndicatorRole,
     RadioButtonRole,

third_party/WebKit/Source/core/accessibility/AXRenderObject.cpp

@@ -409,6 +409,9 @@ AccessibilityRole AXRenderObject::determineAccessibilityRole()
     if (node && node->hasTagName(asideTag))
         return ComplementaryRole;
 
+    if (node && node->hasTagName(preTag))
+        return PreRole;
+
     if (node && node->hasTagName(sectionTag))
         return RegionRole;
 

third_party/WebKit/Source/web/AssertMatchingEnums.cpp

@@ -251,6 +251,7 @@ COMPILE_ASSERT_MATCHING_ENUM(WebAXRoleNote, NoteRole);
 COMPILE_ASSERT_MATCHING_ENUM(WebAXRoleOutline, OutlineRole);
 COMPILE_ASSERT_MATCHING_ENUM(WebAXRoleParagraph, ParagraphRole);
 COMPILE_ASSERT_MATCHING_ENUM(WebAXRolePopUpButton, PopUpButtonRole);
+COMPILE_ASSERT_MATCHING_ENUM(WebAXRolePre, PreRole);
 COMPILE_ASSERT_MATCHING_ENUM(WebAXRolePresentational, PresentationalRole);
 COMPILE_ASSERT_MATCHING_ENUM(WebAXRoleProgressIndicator, ProgressIndicatorRole);
 COMPILE_ASSERT_MATCHING_ENUM(WebAXRoleRadioButton, RadioButtonRole);

third_party/WebKit/public/web/WebAXEnums.h

@@ -151,6 +151,7 @@ enum WebAXRole {
     WebAXRoleOutline,
     WebAXRoleParagraph,
     WebAXRolePopUpButton,
+    WebAXRolePre,
     WebAXRolePresentational,
     WebAXRoleProgressIndicator,
     WebAXRoleRadioButton,