Add regression tests from Luke's bug reports. Part 1.

pkg/front_end/lib/src/fasta/messages.dart

Index: pkg/front_end/lib/src/fasta/messages.dart
diff --git a/pkg/front_end/lib/src/fasta/messages.dart b/pkg/front_end/lib/src/fasta/messages.dart
index b48926c00e36537e62891a5895b02c633588c8e4..9cdebc20aeb46ea89ff0e59d1d19f5362c60665c 100644
--- a/pkg/front_end/lib/src/fasta/messages.dart
+++ b/pkg/front_end/lib/src/fasta/messages.dart
@@ -4,7 +4,7 @@
 
 library fasta.messages;
 
-import 'package:kernel/ast.dart' show Location;
+import 'package:kernel/ast.dart' show Library, Location, Program, TreeNode;
 
 import 'util/relativize.dart' show relativizeUri;
 
@@ -92,3 +92,25 @@ String getSourceLine(Location location) {
   return CompilerContext.current.uriToSource[location.file]
       ?.getTextLine(location.line);
 }
+
+Location getLocationFromNode(TreeNode node) {
+  if (node.enclosingProgram == null) {
+    TreeNode parent = node;
+    while (parent != null && parent is! Library) {
+      parent = parent.parent;
+    }
+    if (parent is Library) {
+      // ignore: UNUSED_LOCAL_VARIABLE
+      Program program = new Program(

[Johnni Winther, 2017/06/23 10:51:44]

Maybe remove `Program program = ` and add a comment about the side effect of
creating a Program.

[ahe, 2017/06/23 12:21:51]

I've changed the code to make it more obvious. IMO.

+          libraries: <Library>[parent],
+          uriToSource: CompilerContext.current.uriToSource);
+      Location result = node.location;
+      parent.parent = null;
+      return result;
+    } else {
+      return null;
+    }
+  } else {
+    return node.location;
+  }
+}