Text nodes: Disallow the "$" character in identifiers

The "$" character will mark text nodes in the future.

lib/parser.js

@@ -1383,17 +1383,6 @@ module.exports = (function(){
               matchFailed("\"_\"");
             }
           }
-          if (r3 === null) {
-            if (input.charCodeAt(pos) === 36) {
-              r3 = "$";
-              pos++;
-            } else {
-              r3 = null;
-              if (reportFailures === 0) {
-                matchFailed("\"$\"");
-              }
-            }
-          }
         }
         if (r3 !== null) {
           r4 = [];
@@ -1410,17 +1399,6 @@ module.exports = (function(){
                   matchFailed("\"_\"");
                 }
               }
-              if (r5 === null) {
-                if (input.charCodeAt(pos) === 36) {
-                  r5 = "$";
-                  pos++;
-                } else {
-                  r5 = null;
-                  if (reportFailures === 0) {
-                    matchFailed("\"$\"");
-                  }
-                }
-              }
             }
           }
           while (r5 !== null) {
@@ -1438,17 +1416,6 @@ module.exports = (function(){
                     matchFailed("\"_\"");
                   }
                 }
-                if (r5 === null) {
-                  if (input.charCodeAt(pos) === 36) {
-                    r5 = "$";
-                    pos++;
-                  } else {
-                    r5 = null;
-                    if (reportFailures === 0) {
-                      matchFailed("\"$\"");
-                    }
-                  }
-                }
               }
             }
           }

spec/parser.spec.js

@@ -349,11 +349,9 @@ describe("PEG.js grammar parser", function() {
   it("parses identifier", function() {
     expect('start = a'   ).toParseAs(ruleRefGrammar("a"));
     expect('start = _'   ).toParseAs(ruleRefGrammar("_"));
-    expect('start = $'   ).toParseAs(ruleRefGrammar("$"));
     expect('start = aa'  ).toParseAs(ruleRefGrammar("aa"));
     expect('start = a0'  ).toParseAs(ruleRefGrammar("a0"));
     expect('start = a_'  ).toParseAs(ruleRefGrammar("a_"));
-    expect('start = a$'  ).toParseAs(ruleRefGrammar("a$"));
     expect('start = abcd').toParseAs(ruleRefGrammar("abcd"));
 
     expect('start = a\n').toParseAs(ruleRefGrammar("a"));

src/parser.pegjs

@@ -190,9 +190,12 @@ dot       = "." __ { return "."; }
  *
  * The simplifications were made just to make the implementation little bit
  * easier, there is no "philosophical" reason behind them.
+ *
+ * Contrary to ECMA 262, the "$" character is not valid because it serves other
+ * purpose in the grammar.
  */
 identifier "identifier"
-  = head:(letter / "_" / "$") tail:(letter / digit / "_" / "$")* __ {
+  = head:(letter / "_") tail:(letter / digit / "_")* __ {
       return head + tail.join("");
     }