Add support for asynchronous event notification to the observatory.

runtime/bin/vmservice/client/lib/src/elements/script_inset.dart

Index: runtime/bin/vmservice/client/lib/src/elements/script_inset.dart
diff --git a/runtime/bin/vmservice/client/lib/src/elements/script_inset.dart b/runtime/bin/vmservice/client/lib/src/elements/script_inset.dart
index cffe42e83152707149b37bb4707a02ddfa308351..5a0c9a7364f7e11d63dfbb6510c4d2265b3a3a26 100644
--- a/runtime/bin/vmservice/client/lib/src/elements/script_inset.dart
+++ b/runtime/bin/vmservice/client/lib/src/elements/script_inset.dart
@@ -72,7 +72,7 @@ class ScriptInsetElement extends ObservatoryElement {
     startLine =
         (pos != null) ? script.tokenToLine(pos) - 1 : 0;
     endLine =
-        (endPos != null) ? script.tokenToLine(endPos) : script.lines.length;
+        (endPos != null) ? script.tokenToLine(endPos) : startLine + 1;
     // Add line numbers.
     lineNumbers.clear();
     for (var i = startLine; i < endLine; i++) {