Make try/catch/finally work with Kernel code and some refactoring.

pkg/compiler/lib/src/ssa/kernel_ast_adapter.dart

Index: pkg/compiler/lib/src/ssa/kernel_ast_adapter.dart
diff --git a/pkg/compiler/lib/src/ssa/kernel_ast_adapter.dart b/pkg/compiler/lib/src/ssa/kernel_ast_adapter.dart
index 3c85ff073254ae904a1e80ac34864caacfd91184..ab928774de9c9f9ed0e360d06057ac6e0b3820cf 100644
--- a/pkg/compiler/lib/src/ssa/kernel_ast_adapter.dart
+++ b/pkg/compiler/lib/src/ssa/kernel_ast_adapter.dart
@@ -354,6 +354,20 @@ class KernelAstAdapter {
   ir.Procedure get mapLiteralUntypedEmptyMaker =>
       kernel.functions[_backend.helpers.mapLiteralUntypedEmptyMaker];
 
+  ir.Procedure get exceptionUnwrapper =>
+      kernel.functions[_backend.helpers.exceptionUnwrapper];
+
+  TypeMask get exceptionUnwrapperType =>
+      TypeMaskFactory.inferredReturnTypeForElement(
+          _backend.helpers.exceptionUnwrapper, _globalInferenceResults);
+
+  ir.Procedure get traceFromException =>
+      kernel.functions[_backend.helpers.traceFromException];
+
+  TypeMask get traceFromExceptionType =>
+      TypeMaskFactory.inferredReturnTypeForElement(
+          _backend.helpers.traceFromException, _globalInferenceResults);
+
   ir.Procedure get mapLiteralUntypedMaker =>
       kernel.functions[_backend.helpers.mapLiteralUntypedMaker];