Use jasmine.DEFAULT_TIMEOUT_INTERVAL for async timeout

Allows a user to specify their desired timeout interval for async specs
and change it on a per spec basis (for particularly slow specs, for example).

As pointed out by @Eric-Wright in #422. [finishes #55996798]

src/core/Spec.js

@@ -58,7 +58,7 @@ getJasmineRequireObj().Spec = function() {
         var timeout = Function.prototype.apply.apply(self.timer.setTimeout, [j$.getGlobal(), [function() {
           onException(new Error('timeout'));
           done();
-        }, 10000]]);
+        }, j$.DEFAULT_TIMEOUT_INTERVAL]]);
 
         var callDone = function() {
           Function.prototype.apply.apply(self.timer.clearTimeout, [j$.getGlobal(), [timeout]]);