Remove default heap size limit and add separate limit for externals.

runtime/vm/pages_test.cc

 // 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/pages.h"
 #include "vm/unit_test.h"
 
 namespace dart {
 
 TEST_CASE(Pages) {
-  PageSpace* space = new PageSpace(NULL, 4 * MBInWords);
+  PageSpace* space = new PageSpace(NULL, 4 * MBInWords, 8 * MBInWords);
   EXPECT(!space->Contains(reinterpret_cast<uword>(&space)));
   uword block = space->TryAllocate(8 * kWordSize);
   EXPECT(block != 0);
   uword total = 0;
   while (total < 2 * MB) {
     const intptr_t kBlockSize = 16 * kWordSize;
     uword new_block = space->TryAllocate(kBlockSize);
     EXPECT(block != 0);
     EXPECT(block != new_block);
     EXPECT(space->IsValidAddress(new_block));
     block = new_block;
     total += kBlockSize;
   }
   // Allocate a large block.
   uword large_block = space->TryAllocate(1 * MB);
   EXPECT(large_block != 0);
   EXPECT(block != large_block);
   EXPECT(space->IsValidAddress(large_block));
   delete space;
 }
 
 }  // namespace dart