Catch corrupted pointers earlier.

Catch corrupted pointers earlier.

Lack of pointer validation made issues 22549 and 22621 more difficult to track down.

Before this change, ScavengePointer would ignore any sufficiently large garbage values, even if they were obviously not well-formed pointers.

Remove obsolete unit test with "foreign" pointers; the zero-size scavenger case is already thoroughly exercised by the VM isolate.

BUG=22621
R=iposva@google.com

Committed: https://code.google.com/p/dart/source/detail?r=44147

[koda, 2015-03-02 17:04:13]

This is actually triggering some unit test failures; looking into whether they
are actual bugs...

[koda, 2015-03-02 18:31:13]

On 2015/03/02 17:04:13, koda wrote:
> This is actually triggering some unit test failures; looking into whether they
> are actual bugs...

Unit tests (trivially) fixed and uploaded. Ready for review.

[Ivan Posva, 2015-03-02 18:38:48]

LGTM -ip

https://codereview.chromium.org/975443003/diff/40001/runtime/vm/scavenger.cc
File runtime/vm/scavenger.cc (right):

https://codereview.chromium.org/975443003/diff/40001/runtime/vm/scavenger.cc#...
runtime/vm/scavenger.cc:159: // TODO(iposva): Add an appropriate assert here or
in the return block
Aren't you addressing this TODO with the assertion below?

[koda, 2015-03-02 19:06:26]

https://codereview.chromium.org/975443003/diff/40001/runtime/vm/scavenger.cc
File runtime/vm/scavenger.cc (right):

https://codereview.chromium.org/975443003/diff/40001/runtime/vm/scavenger.cc#...
runtime/vm/scavenger.cc:159: // TODO(iposva): Add an appropriate assert here or
in the return block
On 2015/03/02 18:38:48, Ivan Posva wrote:
> Aren't you addressing this TODO with the assertion below?

Done.

[koda, 2015-03-02 20:40:39]

Committed patchset #5 (id:80001) manually as r44147 (presubmit successful).