Move assert.h/assert.cc from runtime/vm to runtime/platform

runtime/vm/allocation_test.cc

-// Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
+// Copyright (c) 2012, 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 "platform/assert.h"
 #include "vm/allocation.h"
-#include "vm/assert.h"
 #include "vm/longjump.h"
 #include "vm/unit_test.h"
 
 namespace dart {
 
 class TestValueObject : public ValueObject {
  public:
   explicit TestValueObject(int* ptr) : ptr_(ptr) {
     EXPECT_EQ(1, *ptr_);
     *ptr_ = 2;
@@ skipping 133 matching lines @@
   LongJump jump;
   int data = 1;
   if (setjmp(*jump.Set()) == 0) {
     StackResourceLongJumpHelper(&data, &jump);
     UNREACHABLE();
   }
   EXPECT_EQ(7, data);
 }
 
 }  // namespace dart