Use $$constructor instead of constructor

Standardize the access to the class' constructor, allowing it to be different
from the class constructor function itself.

Author: elia

opal/corelib/array.rb

@@ -237,9 +237,9 @@ def ==(other)
           }
         }
 
-        if (array.constructor !== Array)
+        if (array.$$constructor !== Array)
           array = #{`array`.to_a};
-        if (other.constructor !== Array)
+        if (other.$$constructor !== Array)
           other = #{`other`.to_a};
 
         if (array.length !== other.length) {

opal/corelib/class.rb

@@ -16,7 +16,7 @@ def self.new(superclass = Object, &block)
 
   def allocate
     %x{
-      var obj = new self();
+      var obj = new self.$$constructor();
       obj.$$id = Opal.uid();
       return obj;
     }

opal/corelib/error.rb

@@ -5,7 +5,7 @@ class Exception < `Error`
   def self.new(*args)
     %x{
       var message   = (args.length > 0) ? args[0] : nil;
-      var error     = new self(message);
+      var error     = new self.$$constructor(message);
       error.name    = self.$$name;
       error.message = message;
       Opal.send(error, error.$initialize, args);

opal/corelib/hash.rb

@@ -65,7 +65,7 @@ def self.[](*argv)
 
   def self.allocate
     %x{
-      var hash = new self();
+      var hash = new self.$$constructor();
 
       Opal.hash_init(hash);
 

opal/corelib/runtime.js

@@ -406,7 +406,7 @@
       // calling original JS constructors
       constructor = function() {
         var args = $slice.call(arguments),
-            self = new ($bind.apply(superclass, [null].concat(args)))();
+            self = new ($bind.apply(superclass.$$constructor, [null].concat(args)))();
 
         // and replacing a __proto__ manually
         $setPrototype(self, klass.$$prototype);
@@ -420,6 +420,7 @@
       $defineProperty(constructor, 'displayName', '::'+name);
 
     $defineProperty(klass, '$$name', name);
+    $defineProperty(klass, '$$constructor', constructor);
     $defineProperty(klass, '$$prototype', constructor.prototype);
     $defineProperty(klass, '$$const', {});
     $defineProperty(klass, '$$is_class', true);
@@ -1186,6 +1187,9 @@
     $defineProperty(constructor, '$$ancestors', []);
     $defineProperty(constructor, '$$ancestors_cache_version', null);
     $setPrototype(constructor, Opal.Class.prototype);
+    $defineProperty(constructor, '$$bridge', klass);
+    $defineProperty(klass, 'constructor', constructor);
+    $defineProperty(klass, '$$constructor', constructor);
   };
 
   function protoToModule(proto) {

opal/corelib/string.rb

@@ -9,10 +9,10 @@ class String < `String`
 
     Opal.defineProperty(#{self}.$$prototype, '$$cast', function(string) {
       var klass = this.$$class;
-      if (klass === String) {
+      if (klass.$$constructor === String) {
         return string;
       } else {
-        return new klass(string);
+        return new klass.$$constructor(string);
       }
     });
   }
@@ -29,7 +29,7 @@ def self.try_convert(what)
 
   def self.new(str = '')
     str = Opal.coerce_to(str, String, :to_str)
-    `new self(str)`
+    `new self.$$constructor(str)`
   end
 
   def initialize(str = undefined)