Work around a Gyp bug by creating a stamp file for the http package.

pkg/pkg.gyp

Index: pkg/pkg.gyp
diff --git a/pkg/pkg.gyp b/pkg/pkg.gyp
index d78c4bc879cf2ca8c6982c98eb3cdf11820847f1..dc2b5fef2ea91ceb4592eb5fef95337be77c0459 100644
--- a/pkg/pkg.gyp
+++ b/pkg/pkg.gyp
@@ -43,7 +43,7 @@
           'action_name': 'remove_html_imports',
           'inputs': [
             '../tools/remove_html_imports.py',
-            '<!@(["python", "../tools/list_files.py", "\\.dart$", "http/lib"])',
+            '<(SHARED_INTERMEDIATE_DIR)/http_files.stamp',

[ahe, 2014/08/06 14:15:51]

This target is always run because this file doesn't exist.

To depend on a generated file you need to do two things.

Assume you in target "T1" have action "A1" which generates file "foo.txt", and
you in target "T2" have action "A2" which depends on "foo.txt:

1. List the file as an input of action "A2" (which you have done).

2. List the target "T1" as a dependency of target "T2" (that is missing).

[ahe, 2014/08/06 14:25:55]

That's not correct. It is the action "make_pub_packages" that is always being
run.

Regardless, the problem is with this line. If I manually create
xcodebuild/DerivedSources/ReleaseIA32/http_files.stamp, the action
"make_pub_packages" isn't run when it isn't necessary.

[nweiz, 2014/08/06 21:18:05]

Done.

           ],
           'outputs': [
             '<(SHARED_INTERMEDIATE_DIR)/remove_html_imports/http/lib/http.dart',