dart2js: Bugfix in async rewriter preanalysis.

dart2js: Bugfix in async rewriter preanalysis.

Name and StringConcatenation nodes would be classified as await/yield,
causing their surrounding expressions to be exploded into temporaries.

BUG=
R=sigurdm@google.com

Committed: https://github.com/dart-lang/sdk/commit/b123d5393fb476adb5d11b111d07cd8dc925a7ec

[asgerf, 2015-10-29 11:05:37]

asgerf@google.com changed reviewers:
+ sigurdm@google.com

[asgerf, 2015-10-29 11:05:37]

For example:

list.push(resultA + resultB)

would previously translate to:

$async$temp1 = list;
$async$temp1 = $async$temp1;
$async$temp2 = H;
$async$temp2 = $async$temp2.S(resultA) + " ";
$async$temp3 = H;
$async$temp1.push($async$temp2 + $async$temp3.S(resultB));

and now translates to:

list.push(H.S(resultA) + " " + H.S(resultB));

[sigurdm, 2015-10-29 11:44:21]

Good catch! Thank you
LGTM

[asgerf, 2015-10-29 12:43:14]

Committed patchset #1 (id:1) manually as
b123d5393fb476adb5d11b111d07cd8dc925a7ec (presubmit successful).