Bug 773296 - Part 6: Add enum to represent types of CSS tokens involved in serialization. r=dbaron

This adds an enum to nsCSSScanner.h that represents the types of tokens
we need to consider when pasting together two adjacent tokens during
serialization or variable resolution.  For example with:

  var-a:orange;
  var-b:red;
  color:var(a)var(b);

we need to generate the string "orange/**/red" to parse for the value of
'color'.

layout/style/moz.build

@@ -26,6 +26,7 @@ EXPORTS += [
     'nsCSSPseudoElementList.h',
     'nsCSSPseudoElements.h',
     'nsCSSRuleProcessor.h',
+    'nsCSSScanner.h',
     'nsCSSStyleSheet.h',
     'nsCSSValue.h',
     'nsDOMCSSAttrDeclaration.h',

layout/style/nsCSSScanner.h

@@ -95,6 +95,42 @@ enum nsCSSTokenType {
   eCSSToken_HTMLComment,    // <!-- -->
 };
 
+// Classification of tokens used to determine if a "/**/" string must be
+// inserted if pasting token streams together when serializing.  We include
+// values corresponding to eCSSToken_Dashmatch and eCSSToken_Containsmatch,
+// as css-syntax does not treat these as whole tokens, but we will still
+// need to insert a "/**/" string between a '|' delim and a '|=' dashmatch
+// and between a '/' delim and a '*=' containsmatch.
+//
+// https://dvcs.w3.org/hg/csswg/raw-file/372e659027a0/css-syntax/Overview.html#serialization
+enum nsCSSTokenSerializationType {
+  eCSSTokenSerialization_Nothing,
+  eCSSTokenSerialization_Whitespace,
+  eCSSTokenSerialization_AtKeyword_or_Hash,
+  eCSSTokenSerialization_Number,
+  eCSSTokenSerialization_Dimension,
+  eCSSTokenSerialization_Percentage,
+  eCSSTokenSerialization_URange,
+  eCSSTokenSerialization_URL_or_BadURL,
+  eCSSTokenSerialization_Function,
+  eCSSTokenSerialization_Ident,
+  eCSSTokenSerialization_CDC,
+  eCSSTokenSerialization_DashMatch,
+  eCSSTokenSerialization_ContainsMatch,
+  eCSSTokenSerialization_Symbol_Hash,         // '#'
+  eCSSTokenSerialization_Symbol_At,           // '@'
+  eCSSTokenSerialization_Symbol_Dot_or_Plus,  // '.', '+'
+  eCSSTokenSerialization_Symbol_Minus,        // '-'
+  eCSSTokenSerialization_Symbol_OpenParen,    // '('
+  eCSSTokenSerialization_Symbol_Question,     // '?'
+  eCSSTokenSerialization_Symbol_Assorted,     // '$', '^', '~'
+  eCSSTokenSerialization_Symbol_Equals,       // '='
+  eCSSTokenSerialization_Symbol_Bar,          // '|'
+  eCSSTokenSerialization_Symbol_Slash,        // '/'
+  eCSSTokenSerialization_Symbol_Asterisk,     // '*'
+  eCSSTokenSerialization_Other                // anything else
+};
+
 // A single token returned from the scanner.  mType is always
 // meaningful; comments above describe which other fields are
 // meaningful for which token types.