Fix for bug 5270133 by preventing wrong canonicalization. Fixes problem of sporadic Dart failures...

runtime/vm/object.cc

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/object.h"
 
 #include "vm/assembler.h"
 #include "vm/assert.h"
 #include "vm/bigint_operations.h"
 #include "vm/bootstrap.h"
@@ skipping 6403 matching lines @@
 bool Array::Equals(const Instance& other) const {
   if (this->raw() == other.raw()) {
     // Both handles point to the same raw instance.
     return true;
   }
 
   if (!other.IsArray() || other.IsNull()) {
     return false;
   }
 
+  // Must have the same type.
+  if (GetTypeArguments() != other.GetTypeArguments()) {
+    return false;
+  }
+
   Array& other_arr = Array::Handle();
   other_arr ^= other.raw();
 
   intptr_t len = this->Length();
   if (len != other_arr.Length()) {
     return false;
   }
 
   for (intptr_t i = 0; i < len; i++) {
     if (this->At(i) != other_arr.At(i)) {
@@ skipping 371 matching lines @@
   const String& str = String::Handle(pattern());
   const char* format = "JSRegExp: pattern=%s flags=%s";
   intptr_t len = OS::SNPrint(NULL, 0, format, str.ToCString(), Flags());
   char* chars = reinterpret_cast<char*>(
       Isolate::Current()->current_zone()->Allocate(len + 1));
   OS::SNPrint(chars, (len + 1), format, str.ToCString(), Flags());
   return chars;
 }
 
 }  // namespace dart