Changes "is" and equality checks to strictly check for primitive types, fix a couple of

compiler/lib/implementation/string.js

Index: compiler/lib/implementation/string.js
===================================================================
--- compiler/lib/implementation/string.js	(revision 400)
+++ compiler/lib/implementation/string.js	(working copy)
@@ -15,14 +15,7 @@
 }
 
 function native_StringImplementation_EQ(other) {
-  if (typeof other == 'string') {
-    return this == other;
-  } else if (other instanceof String) {
-    // Must convert other to a primitive for value equality to work.
-    return this == String(other);
-  } else {
-    return false;
-  }
+  return typeof other == 'string' && this == other;
 }
 
 function native_StringImplementation_indexOf(other, startIndex) {