Rearrange String.prototype.indexOf, lastIndexOf and Replace helpers

Fixes issue #515
JerryScript-DCO-1.0-Signed-off-by: Laszlo Vidacs lvidacs.u-szeged@partner.samsung.com

tests/jerry/string-prototype-indexof.js

@@ -85,7 +85,7 @@ assert("Hello world, welcome to the universe.".indexOf("welcome", undefined_var)
 // check booleans
 assert("true".indexOf(true, false) === 0);
 
-// check this is undefined
+// check coercible - undefined
 try {
   String.prototype.indexOf.call(undefined);
   assert(false);
@@ -93,7 +93,7 @@ try {
   assert(e instanceof TypeError);
 }
 
-// check this is null
+// check coercible - null
 try {
   String.prototype.indexOf.call(null);
   assert(false);
@@ -101,24 +101,9 @@ try {
   assert(e instanceof TypeError);
 }
 
-// check coercible - undefined
-try {
-  assert(true.indexOf());
-  assert(false);
-} catch (e) {
-  assert(e instanceof TypeError);
-}
-
-// check coercible - null
-try {
-  assert(isNaN(String.prototype.indexOf.call(null, 0)));
-  assert(false);
-} catch (e) {
-  assert(e instanceof TypeError);
-}
-
 // check coercible - Boolean
 assert(String.prototype.indexOf.call(true, "e") === 3);
+assert(String.prototype.indexOf.call(false, "e") === 4);
 
 // check coercible - Object
 var test_object = {firstName:"John", lastName:"Doe"};