fix(log): prevent logging undefined for $log in IE

Closes #1705

Author: colincasey

src/ng/log.js

@@ -151,7 +151,7 @@ function $LogProvider(){
       // we are IE which either doesn't have window.console => this is noop and we do nothing,
       // or we are IE where console.log doesn't have apply so we log at least first 2 args
       return function(arg1, arg2) {
-        logFn(arg1, arg2);
+        logFn(arg1, arg2 == null ? '' : arg2);
       }
     }
   }];

test/ng/logSpec.js

@@ -69,21 +69,23 @@ describe('$log', function() {
     }
   ));
 
+  describe("IE logging behavior", function() {
+    function removeApplyFunctionForIE() {
+      log.apply = log.call =
+        warn.apply = warn.call =
+        info.apply = info.call =
+        error.apply = error.call =
+        debug.apply = debug.call = null;
 
-  it("should work in IE where console.error doesn't have apply method", inject(
-      function() {
-        log.apply = log.call =
-            warn.apply = warn.call =
-            info.apply = info.call =
-            error.apply = error.call =
-            debug.apply = debug.call = null;
-
-        $window.console = {log: log,
-                           warn: warn,
-                           info: info,
-                           error: error,
-                           debug: debug};
-      },
+      $window.console = {log: log,
+        warn: warn,
+        info: info,
+        error: error,
+        debug: debug};
+    }
+
+    it("should work in IE where console.error doesn't have an apply method", inject(
+      removeApplyFunctionForIE,
       function($log) {
         $log.log.apply($log);
         $log.warn.apply($log);
@@ -92,20 +94,40 @@ describe('$log', function() {
         $log.debug.apply($log);
         expect(logger).toEqual('log;warn;info;error;debug;');
       })
-  );
+    );
+
+    it("should not attempt to log the second argument in IE if it is not specified", inject(
+      function() {
+        log = function(arg1, arg2) { logger+= 'log;' + arg2; };
+        warn = function(arg1, arg2) { logger+= 'warn;' + arg2; };
+        info = function(arg1, arg2) { logger+= 'info;' + arg2; };
+        error = function(arg1, arg2) { logger+= 'error;' + arg2; };
+        debug = function(arg1, arg2) { logger+= 'debug;' + arg2; };
+      },
+      removeApplyFunctionForIE,
+      function($log) {
+        $log.log();
+        $log.warn();
+        $log.info();
+        $log.error();
+        $log.debug();
+        expect(logger).toEqual('log;warn;info;error;debug;');
+      })
+    );
+  });
 
   describe("$log.debug", function () {
-	 
+
 	  beforeEach(initService(false));
-	  
+
 	  it("should skip debugging output if disabled", inject(
 	    function(){
 	      $window.console = {log: log,
 	                         warn: warn,
 	                         info: info,
 	                         error: error,
 	                         debug: debug};
-	    }, 
+	    },
 	    function($log) {
 	      $log.log();
 	      $log.warn();
@@ -115,7 +137,7 @@ describe('$log', function() {
 	      expect(logger).toEqual('log;warn;info;error;');
 	    }
   ));
-	  
+
   });
 
   describe('$log.error', function() {