Fix ESLint errors in lib/compiler/passes/generate-js.js

Fix the following errors:

   65:11  error  Unexpected trailing comma  comma-dangle
  211:40  error  Unexpected trailing comma  comma-dangle
  223:27  error  Unexpected trailing comma  comma-dangle
  233:27  error  Unexpected trailing comma  comma-dangle

lib/compiler/passes/generate-js.js

@@ -62,7 +62,7 @@ function generateJS(ast, options) {
         '',
         'if (cached) {',
         '  peg$currPos = cached.nextPos;',
-        '',
+        ''
       ].join('\n'));
 
       if (options.trace) {
@@ -208,7 +208,7 @@ function generateJS(ast, options) {
       '  return bc;',
       '}',
       '',
-      'function peg$parseRule(index) {',
+      'function peg$parseRule(index) {'
     ].join('\n'));
 
     if (options.trace) {
@@ -220,7 +220,7 @@ function generateJS(ast, options) {
         '      ends     = [],',
         '      stack    = [],',
         '      startPos = peg$currPos,',
-        '      params, i;',
+        '      params, i;'
       ].join('\n'));
     } else {
       parts.push([
@@ -230,7 +230,7 @@ function generateJS(ast, options) {
         '      end   = bc.length,',
         '      ends  = [],',
         '      stack = [],',
-        '      params, i;',
+        '      params, i;'
       ].join('\n'));
     }