Increase the target new space size to the max new space size

Assuming a page creates a low of objects that however will soon die
after page load, delaying the first scavange will hopefully decrease the
amount of time spent during page load without a later penalty when we
have to scavenge a large but mostly dead new space

BUG=v8:3626
R=hpayer@chromium.org
LOG=y

Review URL: https://codereview.chromium.org/721573003

Cr-Commit-Position: refs/heads/master@{#25298}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25298 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/heap/heap.cc

@@ -5040,9 +5040,10 @@ bool Heap::ConfigureHeap(int max_semi_space_size, int max_old_space_size,
     } else {
       target_semispace_size_ = target_semispace_size;
     }
+  } else {
+    target_semispace_size_ = max_semi_space_size_;
   }
 
-  target_semispace_size_ = Max(initial_semispace_size_, target_semispace_size_);
 
   // The old generation is paged and needs at least one page for each space.
   int paged_space_count = LAST_PAGED_SPACE - FIRST_PAGED_SPACE + 1;