Add --modules=node support

tool/node_test.sh

+#!/bin/bash
+set -e
+# switch to the root directory of dev_compiler
+cd $( dirname "${BASH_SOURCE[0]}" )/..
+
+output_dir=tmp/node
+options="--modules=node -o $output_dir"
+
+[[ -d $output_dir ]] || mkdir -p $output_dir
+
+echo "Compiling SDK for node to $output_dir"
+
+./tool/build_sdk.sh $options
+
+function compile() {
+    ./bin/dartdevc.dart $options $1
+}
+function run() {
+    NODE_PATH=$output_dir node --harmony \

[vsm, 2016/01/26 14:09:40]

Do we need "--harmony"?  Looks like most features are just on by default:

https://nodejs.org/en/docs/es6/

[ochafik, 2016/01/26 16:27:37]

Rest params (used in mixins) still need --harmony_rest_parameters (but I'm using
--harmony for simplicity :-))

+        -e "require('dart/_isolate_helper').startRootIsolate(require('$1').main, []);"

[vsm, 2016/01/26 14:09:40]

nit: line len

[ochafik, 2016/01/26 16:27:36]

Done.

+}
+
+# TODO(ochafik): Add full language tests (in separate Travis env/matrix config).
+
+echo "Now compiling hello_dart_test"
+compile test/codegen/language/hello_dart_test.dart
+run hello_dart_test
+
+echo "Now compiling DeltaBlue"
+compile test/codegen/DeltaBlue.dart
+run DeltaBlue