Fix for interpolation codegen bug

Fix for interpolation codegen bug

Also added 'dynamic' version of interpolation test, since original interpolation test was entirely constant-folded.

R=floitsch@google.com

Committed: https://code.google.com/p/dart/source/detail?r=32840

[sra1, 2014-02-19 03:06:22]

https://codereview.chromium.org/171873002/diff/1/sdk/lib/_internal/compiler/i...
File sdk/lib/_internal/compiler/implementation/ssa/nodes.dart (right):

https://codereview.chromium.org/171873002/diff/1/sdk/lib/_internal/compiler/i...
sdk/lib/_internal/compiler/implementation/ssa/nodes.dart:970: bool
isString(Compiler compiler) {
isString now matches the other isXXX methods with respect to nullability, rather
than being opposite.

[sra1, 2014-02-19 03:46:04]

There are ~23 code quality regressions.
About half could be fixed with a stronger annotation on Element.tagName.

Half of the rest could be picked up with better optimizations.

For example:

       if (body == null)
          body = "";
        return Q.View$html("<div class=\"" + cssClass + "\">" + body +
"</div>");
--->
        if (body == null)
          body = "";
        return Q.View$html("<div class=\"" + cssClass + "\">" + H.S(body) +
"</div>");

This might be improved by a fix for http://dartbug.com/16286.

[floitsch, 2014-02-19 12:49:23]

If my assumptions are correct LGTM!

https://codereview.chromium.org/171873002/diff/1/sdk/lib/_internal/compiler/i...
File sdk/lib/_internal/compiler/implementation/ssa/codegen.dart (left):

https://codereview.chromium.org/171873002/diff/1/sdk/lib/_internal/compiler/i...
sdk/lib/_internal/compiler/implementation/ssa/codegen.dart:2051: if
(input.isString(compiler)) {
I assume this was the bad usage?
I furthermore assume, that it worked half of the time, when the value was
"null", but not when it was "undefined".

[sra1, 2014-02-20 02:02:04]

Committed patchset #1 manually as r32840 (presubmit successful).