Implement CSS3 indirect adjacent sibling combinator (~). Roughly identical patches independently written by Daniel Glazman <daniel@glazman.org>, Bradley Baetz <bbaetz@acm.org>, and me. r+sr=dbaron b=135141

content/html/style/src/nsCSSParser.cpp

@@ -1619,7 +1619,9 @@ PRBool CSSParserImpl::ParseSelectorGroup(nsresult& aErrorCode,
     }
 
     if (eCSSToken_Symbol == mToken.mType && 
-        ('+' == mToken.mSymbol || '>' == mToken.mSymbol)) {
+        ('+' == mToken.mSymbol ||
+         '>' == mToken.mSymbol ||
+         '~' == mToken.mSymbol)) {
       done = PR_FALSE;
       combinator = mToken.mSymbol;
       list->mSelectors->SetOperator(combinator);

content/html/style/src/nsCSSStyleSheet.cpp

@@ -3786,6 +3786,12 @@ static PRBool SelectorMatches(RuleProcessorData &data,
   return result;
 }
 
+// Right now, there are four operators:
+//   PRUnichar(0), the descendent combinator, is greedy
+//   '~', the indirect adjacent sibling combinator, is greedy
+//   '+' and '>', the direct adjacent sibling and child combinators, are not
+#define NS_IS_GREEDY_OPERATOR(ch) (ch == PRUnichar(0) || ch == PRUnichar('~'))
+
 static PRBool SelectorMatchesTree(RuleProcessorData& aPrevData,
                                   nsCSSSelector* aSelector) 
 {
@@ -3799,7 +3805,8 @@ static PRBool SelectorMatchesTree(RuleProcessorData& aPrevData,
     // for adjacent sibling combinators, the content to test against the
     // selector is the previous sibling *element*
     RuleProcessorData* data;
-    if (PRUnichar('+') == selector->mOperator) {
+    if (PRUnichar('+') == selector->mOperator ||
+        PRUnichar('~') == selector->mOperator) {
       data = prevdata->mPreviousSiblingData;
       if (!data) {
         nsIContent* content = prevdata->mContent;

content/html/style/src/nsICSSStyleRule.h

@@ -101,11 +101,6 @@ public:
   nsAttrSelector* mNext;
 };
 
-// Right now, there are three operators:
-//   PRUnichar(0), the descendent combinator, is greedy
-//   '+' and '>', the adjacent sibling and child combinators, are not
-#define NS_IS_GREEDY_OPERATOR(ch) ( ch == PRUnichar(0) )
-
 struct nsCSSSelector {
 public:
   nsCSSSelector(void);

layout/style/nsCSSParser.cpp

@@ -1619,7 +1619,9 @@ PRBool CSSParserImpl::ParseSelectorGroup(nsresult& aErrorCode,
     }
 
     if (eCSSToken_Symbol == mToken.mType && 
-        ('+' == mToken.mSymbol || '>' == mToken.mSymbol)) {
+        ('+' == mToken.mSymbol ||
+         '>' == mToken.mSymbol ||
+         '~' == mToken.mSymbol)) {
       done = PR_FALSE;
       combinator = mToken.mSymbol;
       list->mSelectors->SetOperator(combinator);

layout/style/nsCSSStyleSheet.cpp

@@ -3786,6 +3786,12 @@ static PRBool SelectorMatches(RuleProcessorData &data,
   return result;
 }
 
+// Right now, there are four operators:
+//   PRUnichar(0), the descendent combinator, is greedy
+//   '~', the indirect adjacent sibling combinator, is greedy
+//   '+' and '>', the direct adjacent sibling and child combinators, are not
+#define NS_IS_GREEDY_OPERATOR(ch) (ch == PRUnichar(0) || ch == PRUnichar('~'))
+
 static PRBool SelectorMatchesTree(RuleProcessorData& aPrevData,
                                   nsCSSSelector* aSelector) 
 {
@@ -3799,7 +3805,8 @@ static PRBool SelectorMatchesTree(RuleProcessorData& aPrevData,
     // for adjacent sibling combinators, the content to test against the
     // selector is the previous sibling *element*
     RuleProcessorData* data;
-    if (PRUnichar('+') == selector->mOperator) {
+    if (PRUnichar('+') == selector->mOperator ||
+        PRUnichar('~') == selector->mOperator) {
       data = prevdata->mPreviousSiblingData;
       if (!data) {
         nsIContent* content = prevdata->mContent;

layout/style/nsICSSStyleRule.h

@@ -101,11 +101,6 @@ public:
   nsAttrSelector* mNext;
 };
 
-// Right now, there are three operators:
-//   PRUnichar(0), the descendent combinator, is greedy
-//   '+' and '>', the adjacent sibling and child combinators, are not
-#define NS_IS_GREEDY_OPERATOR(ch) ( ch == PRUnichar(0) )
-
 struct nsCSSSelector {
 public:
   nsCSSSelector(void);