Implement type inference for try/catch blocks.

pkg/kernel/lib/core_types.dart

Index: pkg/kernel/lib/core_types.dart
diff --git a/pkg/kernel/lib/core_types.dart b/pkg/kernel/lib/core_types.dart
index 84bf835bd458230d0fa67658a32e217b599477b8..13c1a63417d9c951ee49f31a5ac86e810f9aeece 100644
--- a/pkg/kernel/lib/core_types.dart
+++ b/pkg/kernel/lib/core_types.dart
@@ -71,6 +71,7 @@ class CoreTypes {
 
   Library _asyncLibrary;
   Class _futureClass;
+  Class _stackTraceClass;
   Class _streamClass;
   Class _completerClass;
   Class _futureOrClass;
@@ -235,6 +236,10 @@ class CoreTypes {
     return _printProcedure ??= _index.getTopLevelMember('dart:core', 'print');
   }
 
+  Class get stackTraceClass {
+    return _stackTraceClass ??= _index.getClass('dart:core', 'StackTrace');
+  }
+
   Class get streamClass {
     return _streamClass ??= _index.getClass('dart:async', 'Stream');
   }