perf: use call and === instead of apply and == in type check functions

Updates isDate et al to use call instead of apply and === instead of ==.
The change to call brings minor performance improvement and === is just
better practice than ==.
http://jsperf.com/call-vs-apply-tostring

Closes angular#5295

src/Angular.js

@@ -393,7 +393,7 @@ function valueFn(value) {return function() {return value;};}
  * @param {*} value Reference to check.
  * @returns {boolean} True if `value` is undefined.
  */
-function isUndefined(value){return typeof value == 'undefined';}
+function isUndefined(value){return typeof value === 'undefined';}
 
 
 /**
@@ -407,7 +407,7 @@ function isUndefined(value){return typeof value == 'undefined';}
  * @param {*} value Reference to check.
  * @returns {boolean} True if `value` is defined.
  */
-function isDefined(value){return typeof value != 'undefined';}
+function isDefined(value){return typeof value !== 'undefined';}
 
 
 /**
@@ -422,7 +422,7 @@ function isDefined(value){return typeof value != 'undefined';}
  * @param {*} value Reference to check.
  * @returns {boolean} True if `value` is an `Object` but not `null`.
  */
-function isObject(value){return value != null && typeof value == 'object';}
+function isObject(value){return value != null && typeof value === 'object';}
 
 
 /**
@@ -436,7 +436,7 @@ function isObject(value){return value != null && typeof value == 'object';}
  * @param {*} value Reference to check.
  * @returns {boolean} True if `value` is a `String`.
  */
-function isString(value){return typeof value == 'string';}
+function isString(value){return typeof value === 'string';}
 
 
 /**
@@ -450,7 +450,7 @@ function isString(value){return typeof value == 'string';}
  * @param {*} value Reference to check.
  * @returns {boolean} True if `value` is a `Number`.
  */
-function isNumber(value){return typeof value == 'number';}
+function isNumber(value){return typeof value === 'number';}
 
 
 /**
@@ -465,7 +465,7 @@ function isNumber(value){return typeof value == 'number';}
  * @returns {boolean} True if `value` is a `Date`.
  */
 function isDate(value){
-  return toString.apply(value) == '[object Date]';
+  return toString.call(value) === '[object Date]';
 }
 
 
@@ -481,7 +481,7 @@ function isDate(value){
  * @returns {boolean} True if `value` is an `Array`.
  */
 function isArray(value) {
-  return toString.apply(value) == '[object Array]';
+  return toString.call(value) === '[object Array]';
 }
 
 
@@ -496,7 +496,7 @@ function isArray(value) {
  * @param {*} value Reference to check.
  * @returns {boolean} True if `value` is a `Function`.
  */
-function isFunction(value){return typeof value == 'function';}
+function isFunction(value){return typeof value === 'function';}
 
 
 /**
@@ -507,7 +507,7 @@ function isFunction(value){return typeof value == 'function';}
  * @returns {boolean} True if `value` is a `RegExp`.
  */
 function isRegExp(value) {
-  return toString.apply(value) == '[object RegExp]';
+  return toString.call(value) === '[object RegExp]';
 }
 
 
@@ -529,12 +529,12 @@ function isScope(obj) {
 
 
 function isFile(obj) {
-  return toString.apply(obj) === '[object File]';
+  return toString.call(obj) === '[object File]';
 }
 
 
 function isBoolean(value) {
-  return typeof value == 'boolean';
+  return typeof value === 'boolean';
 }
 
 
@@ -638,7 +638,7 @@ function includes(array, obj) {
 function indexOf(array, obj) {
   if (array.indexOf) return array.indexOf(obj);
 
-  for ( var i = 0; i < array.length; i++) {
+  for (var i = 0; i < array.length; i++) {
     if (obj === array[i]) return i;
   }
   return -1;