Add Chain.foldFrames to pkg/stack_trace.

Add Chain.foldFrames to pkg/stack_trace.

R=rnystrom@google.com
BUG=17082
Committed: https://code.google.com/p/dart/source/detail?r=33041

[Bob Nystrom, 2014-02-25 22:10:59]

https://codereview.chromium.org/180223005/diff/1/pkg/stack_trace/lib/src/chai...
File pkg/stack_trace/lib/src/chain.dart (right):

https://codereview.chromium.org/180223005/diff/1/pkg/stack_trace/lib/src/chai...
pkg/stack_trace/lib/src/chain.dart:189: return trace.frames.length > 1;
Why isn't this .isNotEmpty?

[nweiz, 2014-02-25 22:38:08]

https://codereview.chromium.org/180223005/diff/1/pkg/stack_trace/lib/src/chai...
File pkg/stack_trace/lib/src/chain.dart (right):

https://codereview.chromium.org/180223005/diff/1/pkg/stack_trace/lib/src/chai...
pkg/stack_trace/lib/src/chain.dart:189: return trace.frames.length > 1;
On 2014/02/25 22:10:59, Bob Nystrom wrote:
> Why isn't this .isNotEmpty?

We want to omit chains that contain only a single frame, since that's what we
get if all the frames are folded together.

[Bob Nystrom, 2014-02-25 22:58:31]

lgtm

https://codereview.chromium.org/180223005/diff/1/pkg/stack_trace/lib/src/chai...
File pkg/stack_trace/lib/src/chain.dart (right):

https://codereview.chromium.org/180223005/diff/1/pkg/stack_trace/lib/src/chai...
pkg/stack_trace/lib/src/chain.dart:189: return trace.frames.length > 1;
On 2014/02/25 22:38:08, nweiz wrote:
> On 2014/02/25 22:10:59, Bob Nystrom wrote:
> > Why isn't this .isNotEmpty?
> 
> We want to omit chains that contain only a single frame, since that's what we
> get if all the frames are folded together.

Ah, got it. Clarify the comment then.

[nweiz, 2014-02-25 23:19:46]

https://codereview.chromium.org/180223005/diff/1/pkg/stack_trace/lib/src/chai...
File pkg/stack_trace/lib/src/chain.dart (right):

https://codereview.chromium.org/180223005/diff/1/pkg/stack_trace/lib/src/chai...
pkg/stack_trace/lib/src/chain.dart:189: return trace.frames.length > 1;
On 2014/02/25 22:58:31, Bob Nystrom wrote:
> On 2014/02/25 22:38:08, nweiz wrote:
> > On 2014/02/25 22:10:59, Bob Nystrom wrote:
> > > Why isn't this .isNotEmpty?
> > 
> > We want to omit chains that contain only a single frame, since that's what
we
> > get if all the frames are folded together.
> 
> Ah, got it. Clarify the comment then.

Done.

[nweiz, 2014-02-25 23:20:04]

Committed patchset #3 manually as r33041 (presubmit successful).