Make compiler imports relative in async-compiled code.

sdk/lib/_internal/pub/bin/async_compile.dart

Index: sdk/lib/_internal/pub/bin/async_compile.dart
diff --git a/sdk/lib/_internal/pub/bin/async_compile.dart b/sdk/lib/_internal/pub/bin/async_compile.dart
index 332465be6e8c070843241a6214ca552aff754aec..c40d54d95ceb1b8c9302f5920c93c20d358b4892 100644
--- a/sdk/lib/_internal/pub/bin/async_compile.dart
+++ b/sdk/lib/_internal/pub/bin/async_compile.dart
@@ -175,7 +175,8 @@ String _translateAsyncAwait(String sourcePath, String source) {
 /// to fix those to be valid relative imports from the build directory.
 String _fixDart2jsImports(String sourcePath, String source, String destPath) {
   var compilerDir = p.url.join(sourceUrl, "../compiler");
-  var relative = p.url.relative(compilerDir, from: p.dirname(destPath));
+  var relative = p.url.relative(compilerDir,
+      from: p.dirname(p.toUri(destPath).toString()));

[nweiz, 2014/09/09 19:21:31]

This should be p.url.dirname if it's working on a URL.

   return source.replaceAll(_compilerPattern, "import '$relative");
 }