src/emitter.js: Sync |escape| in generated parsers with utils.js

Fixes the following JSHint errors:

  ./src/parser.js: line 102, col 26, 'escapeChar' is already defined.
  ./src/parser.js: line 103, col 22, 'length' is already defined.
  ./src/parser.js: line 106, col 23, 'escapeChar' used out of scope.
  ./src/parser.js: line 106, col 86, 'length' used out of scope.

src/emitter.js

@@ -141,13 +141,15 @@ PEG.compiler.emitter = function(ast) {
         /* This needs to be in sync with |escape| in utils.js. */
         "      function escape(ch) {",
         "        var charCode = ch.charCodeAt(0);",
+        "        var escapeChar;",
+        "        var length;",
         "        ",
         "        if (charCode <= 0xFF) {",
-        "          var escapeChar = 'x';",
+        "          escapeChar = 'x';",
-        "          var length = 2;",
+        "          length = 2;",
         "        } else {",
-        "          var escapeChar = 'u';",
+        "          escapeChar = 'u';",
-        "          var length = 4;",
+        "          length = 4;",
         "        }",
         "        ",
         "        return '\\\\' + escapeChar + padLeft(charCode.toString(16).toUpperCase(), '0', length);",

src/parser.js

@@ -94,13 +94,15 @@ PEG.parser = (function(){
       
       function escape(ch) {
         var charCode = ch.charCodeAt(0);
+        var escapeChar;
+        var length;
         
         if (charCode <= 0xFF) {
-          var escapeChar = 'x';
+          escapeChar = 'x';
-          var length = 2;
+          length = 2;
         } else {
-          var escapeChar = 'u';
+          escapeChar = 'u';
-          var length = 4;
+          length = 4;
         }
         
         return '\\' + escapeChar + padLeft(charCode.toString(16).toUpperCase(), '0', length);