Clean up various ways we find paths in pub.

This makes it so that it's never necessary to pass in DART_SDK.

Review URL: https://codereview.chromium.org//14449004

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart/pkg/stack_trace@21914 260f80e4-7a28-3924-810f-c04153c831b5

pkgs/stack_trace/lib/src/utils.dart

diff --git a/pkgs/stack_trace/lib/src/utils.dart b/pkgs/stack_trace/lib/src/utils.dart
index 790dec8..ec764e5 100644
--- a/pkgs/stack_trace/lib/src/utils.dart
+++ b/pkgs/stack_trace/lib/src/utils.dart
@@ -15,7 +15,14 @@
     throw new ArgumentError("Uri $uri must have scheme 'file:'.");
   }
   if (Platform.operatingSystem != 'windows') return uri.path;
-  return uri.path.replaceFirst("/", "").replaceAll("/", "\\");
+  if (uri.path.startsWith("/")) {
+    // Drive-letter paths look like "file:///C:/path/to/file". The replaceFirst
+    // removes the extra initial slash.
+    return uri.path.replaceFirst("/", "").replaceAll("/", "\\");
+  } else {
+    // Network paths look like "file://hostname/path/to/file".
+    return "\\\\${uri.path.replaceAll("/", "\\")}";
+  }
 }
 
 /// Converts a local path string to a `file:` [Uri].
@@ -23,7 +30,11 @@
   pathString = path.absolute(pathString);
   if (Platform.operatingSystem != 'windows') {
     return Uri.parse('file://$pathString');
+  } else if (path.rootPrefix(path).startsWith('\\\\')) {
+    // Network paths become "file://hostname/path/to/file".
+    return Uri.parse('file:${pathString.replaceAll("\\", "/")}');
   } else {
+    // Drive-letter paths become "file:///C:/path/to/file".
     return Uri.parse('file:///${pathString.replaceAll("\\", "/")}');
   }
 }