Update audit.js and fix error catching logic in should().throw()

Fetch/update audit.js in non-WPT layout tests and also fix the error
in the error catching logic in should().throw() assertion.

The updated code checks if the |error| object passed by try/catch
is "DOMException". This is unnecessarily specific, so this CL changes
the check to look for the "Error" type, which is more generic.

Bug: 865614
Test: All layout tests pass.
Change-Id: I16acacb26c194a0ff950aca05e931195bf55167f

webaudio/resources/audit.js

@@ -275,9 +275,8 @@ window.Audit = (function() {
     /**
      * Check if |actual| operation wrapped in a function throws an exception
      * with a expected error type correctly. |expected| is optional. If it is a
-     * String, then it is considered to be the name of a DOMException. It can
-     * also be an instance of either an Error or a DOMException, to be more
-     * strict about the actual error type.
+     * String, then it is considered to be the name of an Error. It can also be
+     * an instance of an Error to be more strict about the actual error type.
      *
      * @example
      *   should(() => { let a = b; }, 'A bad code').throw();
@@ -313,10 +312,10 @@ window.Audit = (function() {
           // The expected error type was not given.
           didThrowCorrectly = true;
           passDetail = '${actual} threw ' + error.name + errorMessage + '.';
-        } else if (typeof(this._expected) == "string" &&
-                   error instanceof DOMException &&
+        } else if (typeof this._expected === "string" &&
+                   error instanceof Error &&
                    error.name === this._expected) {
-          // A DOMException was thrown and expected, and the names match
+          // An |Error| was thrown and expected, and the names match.
           didThrowCorrectly = true;
           passDetail = '${actual} threw ${expected}' + errorMessage + '.';
         } else if (this._expected == error.constructor &&