spyOn explicitly checks to see that a method name to spy on was passed.

[finish #27689237]

src/core/SpyRegistry.js

@@ -9,6 +9,10 @@ getJasmineRequireObj().SpyRegistry = function(j$) {
         throw new Error('spyOn could not find an object to spy upon for ' + methodName + '()');
       }
 
+      if (j$.util.isUndefined(methodName)) {
+        throw new Error('No method name supplied');
+      }
+
       if (j$.util.isUndefined(obj[methodName])) {
         throw new Error(methodName + '() method does not exist');
       }