Add a WebDocument::watchCssSelectors(selectors)

Source/core/css/CSSParser-in.cpp

Index: Source/core/css/CSSParser-in.cpp
diff --git a/Source/core/css/CSSParser-in.cpp b/Source/core/css/CSSParser-in.cpp
index ff6a7589e8177690d4c7b45f030fd15847f1522d..fd1a4a02eadbba3a307a88655427a585df69710b 100644
--- a/Source/core/css/CSSParser-in.cpp
+++ b/Source/core/css/CSSParser-in.cpp
@@ -778,6 +778,9 @@ static inline bool isValidKeywordPropertyAndValue(CSSPropertyID propertyId, int
         if (valueID == CSSValueStart || valueID == CSSValueEnd || valueID == CSSValueCenter || valueID == CSSValueJustify)
             return true;
         break;
+    case CSSPropertyInternalCallback:
+        // This property is only injected programmatically, not parsed from stylesheets.
+        return false;
     case CSSPropertyAlignContent:
          if (valueID == CSSValueFlexStart || valueID == CSSValueFlexEnd || valueID == CSSValueCenter || valueID == CSSValueSpaceBetween || valueID == CSSValueSpaceAround || valueID == CSSValueStretch)
              return true;
@@ -989,6 +992,7 @@ static inline bool isKeywordPropertyID(CSSPropertyID propertyId)
     case CSSPropertyWebkitBoxLines:
     case CSSPropertyWebkitBoxOrient:
     case CSSPropertyWebkitBoxPack:
+    case CSSPropertyInternalCallback:
     case CSSPropertyWebkitColumnBreakAfter:
     case CSSPropertyWebkitColumnBreakBefore:
     case CSSPropertyWebkitColumnBreakInside:
@@ -2814,6 +2818,7 @@ bool CSSParser::parseValue(CSSPropertyID propId, bool important)
     case CSSPropertyWebkitBoxLines:
     case CSSPropertyWebkitBoxOrient:
     case CSSPropertyWebkitBoxPack:
+    case CSSPropertyInternalCallback:
     case CSSPropertyWebkitColumnBreakAfter:
     case CSSPropertyWebkitColumnBreakBefore:
     case CSSPropertyWebkitColumnBreakInside: