Use UglifyJS 2.4.7

The |uglifyjs| call had to be adapted because the options changed
significantly in version 2.

Makefile

@@ -106,7 +106,12 @@ browser:
 	echo '  return modules["peg"]' >> $(BROWSER_FILE_DEV)
 	echo '})();'                   >> $(BROWSER_FILE_DEV)
 
-	$(UGLIFYJS) --ascii -o $(BROWSER_FILE_MIN) $(BROWSER_FILE_DEV)
+	$(UGLIFYJS)                 \
+	  --mangle                  \
+	  --compress warnings=false \
+	  --comments /Copyright/    \
+	  -o $(BROWSER_FILE_MIN)    \
+	  $(BROWSER_FILE_DEV)
 
 # Remove browser version of the library (created by "browser")
 browserclean:

package.json

@@ -42,7 +42,7 @@
   },
   "devDependencies": {
     "jasmine-node": "= 1.11.0",
-    "uglify-js":    "= 1.3.4",
+    "uglify-js":    "= 2.4.7",
     "jshint":       "= 0.9.1"
   },
   "engines":         {