#1015 use isNumber fuction to check for empty expected argument. This will allow 0 to be passed in.

src/core/matchers/toHaveBeenCalledTimes.js

@@ -10,8 +10,8 @@ getJasmineRequireObj().toHaveBeenCalledTimes = function(j$) {
         var args = Array.prototype.slice.call(arguments, 0),
           result = { pass: false };
 
-        if(!expected){
-          throw new Error('Expected times failed is required as an argument.');
+        if (!j$.isNumber_(expected)){
+          throw new Error('The expected times failed is a required argument and must be a number.');
         }
 
         actual = args[0];
@@ -27,4 +27,4 @@ getJasmineRequireObj().toHaveBeenCalledTimes = function(j$) {
   }
 
   return toHaveBeenCalledTimes;
-};
+};