Type check try statements

sdk/lib/_internal/compiler/implementation/compiler.dart

Index: sdk/lib/_internal/compiler/implementation/compiler.dart
diff --git a/sdk/lib/_internal/compiler/implementation/compiler.dart b/sdk/lib/_internal/compiler/implementation/compiler.dart
index 1452eff873768f2ada6745a244b7e1629eb496ff..5afc41de52b0917dd90914622c35f5616d25a993 100644
--- a/sdk/lib/_internal/compiler/implementation/compiler.dart
+++ b/sdk/lib/_internal/compiler/implementation/compiler.dart
@@ -318,6 +318,7 @@ abstract class Compiler implements DiagnosticListener {
   ClassElement typeClass;
   ClassElement mapClass;
   ClassElement symbolClass;
+  ClassElement stackTraceClass;
 
   // Initialized after mirrorSystemClass has been resolved.
   FunctionElement symbolConstructor;
@@ -680,6 +681,7 @@ abstract class Compiler implements DiagnosticListener {
     listClass = lookupCoreClass('List');
     typeClass = lookupCoreClass('Type');
     mapClass = lookupCoreClass('Map');
+    stackTraceClass = lookupCoreClass('StackTrace');
     if (!missingCoreClasses.isEmpty) {
       internalErrorOnElement(coreLibrary,
           'dart:core library does not contain required classes: '
@@ -1109,7 +1111,9 @@ abstract class Compiler implements DiagnosticListener {
     if (Elements.isErroneousElement(element)) {
       element = element.enclosingElement;
     }
-    if (element.position() == null && !element.isCompilationUnit()) {
+    if (element.position() == null &&
+        !element.isLibrary() &&
+        !element.isCompilationUnit()) {
       // Sometimes, the backend fakes up elements that have no
       // position. So we use the enclosing element instead. It is
       // not a good error location, but cancel really is "internal