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..9d1943d8eb1dcd91882b8541fb57781df4e4670c 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 +92,26 @@ 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) {
+      Program program =
+          new Program(uriToSource: CompilerContext.current.uriToSource);
+      program.libraries.add(parent);
+      parent.parent = program;
+      Location result = node.location;
+      program.libraries.clear();
+      parent.parent = null;
+      return result;
+    } else {
+      return null;
+    }
+  } else {
+    return node.location;
+  }
+}