Go back to doubling the size when growing new space.

Our memory tests show little improvement by only growing by 50%.

Review URL: http://codereview.chromium.org/174133

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@2728 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/spaces.cc

@@ -1079,9 +1079,9 @@ void SemiSpace::TearDown() {
 
 
 bool SemiSpace::Grow() {
-  // Commit 50% extra space but only up to maximum capacity.
+  // Double the semispace size but only up to maximum capacity.
   int maximum_extra = maximum_capacity_ - capacity_;
-  int extra = Min(RoundUp(capacity_ / 2, OS::AllocateAlignment()),
+  int extra = Min(RoundUp(capacity_, OS::AllocateAlignment()),
                   maximum_extra);
   if (!MemoryAllocator::CommitBlock(high(), extra, executable())) {
     return false;

src/v8.cc

@@ -156,6 +156,7 @@ uint32_t V8::Random() {
   return (hi << 16) + (lo & 0xFFFF);
 }
 
+
 void V8::IdleNotification(bool is_high_priority) {
   if (!FLAG_use_idle_notification) return;
   // Ignore high priority instances of V8.