Distinguish statement and expression foreign code.

Distinguish statement and expression foreign code.

Committed: https://code.google.com/p/dart/source/detail?r=9159

[floitsch, 2012-06-25 12:45:08]

I tested this by adding parenthesis ("(", ")") around all foreign expressions
and curly braces around the statements.

[floitsch, 2012-06-25 15:39:41]

Turns out that we need the parenthesis around foreigns now.
The reason: when transforming "if"s into "&&"s we set the right-hand-side to
operatorPrecedence.right. However we then visit the rhs with
"visitWithoutIndent" which will eventually go through iterateBasicBlock where
the precedence is "reset" to STATEMENT_PRECEDENCE.
It seems that we only allowed exrpessions as rhs that didn't need parenthesis
and that's why we didn't notice it.
With foreigns being expressions we now have cases where the foreign-node
assigns, and then the precedence is not set up correctly.
In fact we had:
!(x === null) && a = b;  // "a = b" is foreign.
instead of
!(x === null) && (a = b); // or
if (x !== null) a = b;

By adding the parenthesis we don't fix the underlying problem, but we don't have
errors anymore.

Created issue 3862.

[Lasse Reichstein Nielsen, 2012-06-26 14:11:27]

LGTM.

The ultimate hack would be making JS take a precedence parameter, and
parenthesize it from that.
Or build a JS AST instead of just doing textual substitution.

[floitsch, 2012-06-26 16:37:53]

After https://chromiumcodereview.appspot.com/10669035/ we don't the parenthesis
anymore.
PTAL.

[Lasse Reichstein Nielsen, 2012-06-27 08:10:16]

Shouldn't there be something in codegen that outputs the removed ';' for
statements?

Otherwise LGTM.

http://codereview.chromium.org/10668021/diff/5002/lib/compiler/implementation...
File lib/compiler/implementation/ssa/nodes.dart (right):

http://codereview.chromium.org/10668021/diff/5002/lib/compiler/implementation...
lib/compiler/implementation/ssa/nodes.dart:1324: final bool _isStatement;
Just make this non-private and final. No need to wrap a final field in a getter.
And make isStatement a getter, obviously :)

[floitsch, 2012-06-27 12:04:43]

The semicolon was double. So no need to compensate anywhere.

http://codereview.chromium.org/10668021/diff/5002/lib/compiler/implementation...
File lib/compiler/implementation/ssa/nodes.dart (right):

http://codereview.chromium.org/10668021/diff/5002/lib/compiler/implementation...
lib/compiler/implementation/ssa/nodes.dart:1324: final bool _isStatement;
On 2012/06/27 08:10:16, Lasse Reichstein Nielsen wrote:
> Just make this non-private and final. No need to wrap a final field in a
getter.
> And make isStatement a getter, obviously :)

Done.