Accelerate old-space growth

Use history to estimate what fraction of allocation will be garbage => grow more when less garbage was collected.

Change semantics of heap_growth_rate flag to mean *maximum* number of pages we grow.

Allow more initial growth before first mark-sweep => many small programs will avoid mark-sweep.

R=iposva@google.com

Committed: https://code.google.com/p/dart/source/detail?r=35410

[koda, 2014-04-22 16:44:43]

Updated with an "initial gc timeout" to avoid wasting space for slow-allocating
isolates.

With current default params: first gc happens after at most 32 MB of allocation,
but after 1 second, that limit begins to decrease geometrically, so after 2
seconds, the limit is 16 MB, etc.

This does not affect fast-growing programs like dart2js.

[Ivan Posva, 2014-04-24 17:44:18]

LGTM -ip

https://codereview.chromium.org/235343004/diff/80001/runtime/vm/pages.cc
File runtime/vm/pages.cc (right):

https://codereview.chromium.org/235343004/diff/80001/runtime/vm/pages.cc#newc...
runtime/vm/pages.cc:683: Heap* heap = Isolate::Current()->heap();
The PSC should remember the heap it is associated with, so you don't have to do
this.

[koda, 2014-04-24 18:07:45]

https://codereview.chromium.org/235343004/diff/80001/runtime/vm/pages.cc
File runtime/vm/pages.cc (right):

https://codereview.chromium.org/235343004/diff/80001/runtime/vm/pages.cc#newc...
runtime/vm/pages.cc:683: Heap* heap = Isolate::Current()->heap();
On 2014/04/24 17:44:18, Ivan Posva wrote:
> The PSC should remember the heap it is associated with, so you don't have to
do
> this.

I'll do this in a follow-up Isolate::Current clean-up CL that adds an isolate_
field to Heap.

[koda, 2014-04-24 22:30:31]

Committed patchset #5 manually as r35410 (presubmit successful).