Adjust the brace-style ESLint rule to disallow single lines (and also enable no-iterator)

See http://eslint.org/docs/rules/brace-style.
Having the opening/closing braces on the same line can often make the code slightly more difficult to read, in particular for `if`/`else if` statements, compared to using new lines.

This patch also, for consistency with `mozilla-central`, enables the [`no-iterator`](http://eslint.org/docs/rules/no-iterator) rule. Note that this rule didn't require a single code change.

src/display/global.js

@@ -68,8 +68,12 @@
   }
   delete PDFJS.verbosity;
   Object.defineProperty(PDFJS, 'verbosity', {
-    get: function () { return sharedUtil.getVerbosityLevel(); },
-    set: function (level) { sharedUtil.setVerbosityLevel(level); },
+    get: function () {
+      return sharedUtil.getVerbosityLevel();
+    },
+    set: function (level) {
+      sharedUtil.setVerbosityLevel(level);
+    },
     enumerable: true,
     configurable: true
   });