Add support for exception rethrowing using "throw;"

Add support for exception rethrowing using "throw;"
Committed: https://code.google.com/p/dart/source/detail?r=372

[jat, 2011-10-12 17:29:55]

LGTM

Pending resolution of proper behavior for a rethrow outside of a catch.

http://codereview.chromium.org/8208016/diff/1/compiler/java/com/google/dart/c...
File
compiler/java/com/google/dart/compiler/backend/js/GenerateJavascriptAST.java
(right):

http://codereview.chromium.org/8208016/diff/1/compiler/java/com/google/dart/c...
compiler/java/com/google/dart/compiler/backend/js/GenerateJavascriptAST.java:2045:
if (name != null) {
Could name be null anytime besides a re-throw outside of any catch block?

http://codereview.chromium.org/8208016/diff/1/compiler/java/com/google/dart/c...
compiler/java/com/google/dart/compiler/backend/js/GenerateJavascriptAST.java:2049:
exception = string("invalid rethrow");
It seems like this should be a compile-time error (unless there is a case I am
missing):

foo() {
  throw;
}

I would expect a "re-throw not inside catch block" compile-time error, rather
than throwing a compiler-defined string.

[John Lenz, 2011-10-12 17:34:06]

http://codereview.chromium.org/8208016/diff/1/compiler/java/com/google/dart/c...
File
compiler/java/com/google/dart/compiler/backend/js/GenerateJavascriptAST.java
(right):

http://codereview.chromium.org/8208016/diff/1/compiler/java/com/google/dart/c...
compiler/java/com/google/dart/compiler/backend/js/GenerateJavascriptAST.java:2045:
if (name != null) {
On 2011/10/12 17:29:55, jat wrote:
> Could name be null anytime besides a re-throw outside of any catch block?

No.

http://codereview.chromium.org/8208016/diff/1/compiler/java/com/google/dart/c...
compiler/java/com/google/dart/compiler/backend/js/GenerateJavascriptAST.java:2049:
exception = string("invalid rethrow");
On 2011/10/12 17:29:55, jat wrote:
> It seems like this should be a compile-time error (unless there is a case I am
> missing):

Yes, it should be a compile time error, but I'm unsure of our requirements to
generate code in the face of invalid input.  This guarantees that we generate
valid JS.
> 
> foo() {
>   throw;
> }
> 
> I would expect a "re-throw not inside catch block" compile-time error, rather
> than throwing a compiler-defined string.

[jat, 2011-10-12 18:01:28]

LGTM