Serialize metadata

pkg/compiler/lib/src/compiler.dart

Index: pkg/compiler/lib/src/compiler.dart
diff --git a/pkg/compiler/lib/src/compiler.dart b/pkg/compiler/lib/src/compiler.dart
index 234c7e17f18c0257c13e2c37efd79c06ba87af7f..94b573a422ddc5cc9fcc449ebd2af964a4cd4c8f 100644
--- a/pkg/compiler/lib/src/compiler.dart
+++ b/pkg/compiler/lib/src/compiler.dart
@@ -1658,8 +1658,9 @@ class CompilerDiagnosticReporter extends DiagnosticReporter {
           if (astElement.hasNode) {
             Token from = astElement.node.getBeginToken();
             Token to = astElement.node.getEndToken();
-            if (astElement.metadata.isNotEmpty) {
-              from = astElement.metadata.first.beginToken;
+            if (astElement.metadata.isNotEmpty &&
+                astElement.metadata.first.hasNode) {
+              from = astElement.metadata.first.node.getBeginToken();
             }
             return validateToken(from, to);
           }
@@ -1740,8 +1741,7 @@ class CompilerDiagnosticReporter extends DiagnosticReporter {
     } else if (node is Element) {
       return spanFromElement(node);
     } else if (node is MetadataAnnotation) {
-      Uri uri = node.annotatedElement.compilationUnit.script.resourceUri;
-      return spanFromTokens(node.beginToken, node.endToken, uri);
+      return node.sourcePosition;
     } else if (node is Local) {
       Local local = node;
       return spanFromElement(local.executableContext);