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 0e45c5c3823153039f0374dbb2109765b02dd9b1..1db8830c0b04945c9797a8bb1e1573cc9c1bd180 100644
--- a/Source/core/css/CSSParser-in.cpp
+++ b/Source/core/css/CSSParser-in.cpp
@@ -770,6 +770,9 @@ 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;
@@ -980,6 +983,7 @@ static inline bool isKeywordPropertyID(CSSPropertyID propertyId)
     case CSSPropertyWebkitBoxLines:
     case CSSPropertyWebkitBoxOrient:
     case CSSPropertyWebkitBoxPack:
+    case CSSPropertyInternalCallback:
     case CSSPropertyWebkitColumnBreakAfter:
     case CSSPropertyWebkitColumnBreakBefore:
     case CSSPropertyWebkitColumnBreakInside:
@@ -2784,6 +2788,7 @@ bool CSSParser::parseValue(CSSPropertyID propId, bool important)
     case CSSPropertyWebkitBoxLines:
     case CSSPropertyWebkitBoxOrient:
     case CSSPropertyWebkitBoxPack:
+    case CSSPropertyInternalCallback:
     case CSSPropertyWebkitColumnBreakAfter:
     case CSSPropertyWebkitColumnBreakBefore:
     case CSSPropertyWebkitColumnBreakInside: