Adapt Random class to be able to run in javascript integer compatibility mode.

Adapt Random class to be able to run in javascript integer compatibility mode.

R=asiva@google.com, zra@google.com

Committed: https://code.google.com/p/dart/source/detail?r=25753

[zra, 2013-08-02 21:22:22]

lgtm with question.

https://codereview.chromium.org/21966003/diff/1/runtime/vm/object.h
File runtime/vm/object.h (right):

https://codereview.chromium.org/21966003/diff/1/runtime/vm/object.h#newcode5352
runtime/vm/object.h:5352: TypedDataElementType ElementType() const {
Is this renaming related to the Random fix?

[siva, 2013-08-02 22:46:13]

As discussed offline I have a question about
the use of Uint64 TypedData to do the same in Dart.
Which lead to the general discussion about how to we
handle Int64 and Uint64 TypedData with this flag turned on.

LGTM for now, we can discuss this next week.

https://codereview.chromium.org/21966003/diff/1/runtime/lib/math.cc
File runtime/lib/math.cc (right):

https://codereview.chromium.org/21966003/diff/1/runtime/lib/math.cc#newcode77
runtime/lib/math.cc:77:
Instance::Cast(Object::Handle(receiver.GetField(state_field)));
Why cast this to an Instance, it is being cast to TypedData below
why not just retain it as an Object:

const Object& state_field_value = Object::Handle(...);

https://codereview.chromium.org/21966003/diff/1/runtime/lib/math.cc#newcode95
runtime/lib/math.cc:95: const uint64_t state_hi =
array.GetUint32(array.ElementSizeInBytes());
might be more readable to have:
const intptr_t state_lo_offset = 0;
const intptr_t state_hi_offset = 1 * array.ElementSizeInBytes();
and use these in GetUint32(...) and SetUint32(...)

https://codereview.chromium.org/21966003/diff/1/runtime/lib/math.cc#newcode123
runtime/lib/math.cc:123: array.SetUint32(array.ElementSizeInBytes(),
Ditto comment about offsets.

[srdjan, 2013-08-02 23:08:00]

Committed patchset #1 manually as r25753 (presubmit successful).