Fix first part on liveness analysis of bug https://code.google.com/p/dart/issues/detail?id=9687: a …

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

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of ssa;
 
 class HValidator extends HInstructionVisitor {
   bool isValid = true;
   HGraph graph;
 
@@ skipping 26 matching lines @@
     }
     if (block.last is HConditionalBranch && block.successors.length != 2) {
       markInvalid("Conditional node without two successors");
     }
     if (block.last is HGoto && block.successors.length != 1) {
       markInvalid("Goto node with not exactly one successor");
     }
     if (block.last is HJump && block.successors.length != 1) {
       markInvalid("Break or continue node without one successor");
     }
-    if (block.last is HReturn &&
+    if ((block.last is HReturn || block.last is HThrow) &&
         (block.successors.length != 1 || !block.successors[0].isExitBlock())) {
-      markInvalid("Return node with > 1 succesor or not going to exit-block");
+      markInvalid("Return or throw node with > 1 successor "
+                  "or not going to exit-block");
     }
     if (block.last is HExit && !block.successors.isEmpty) {
       markInvalid("Exit block with successor");
     }
-    if (block.last is HThrow && !block.successors.isEmpty) {
-      markInvalid("Throw block with successor");
-    }
 
-    if (block.successors.isEmpty &&
-        block.last is !HThrow &&
-        !block.isExitBlock()) {
-      markInvalid("Non-exit or throw block without successor");
+    if (block.successors.isEmpty && !block.isExitBlock()) {
+      markInvalid("Non-exit block without successor");
     }
 
     // Check that successors ids are always higher than the current one.
     // TODO(floitsch): this is, of course, not true for back-branches.
     if (block.id == null) markInvalid("block without id");
     for (HBasicBlock successor in block.successors) {
       if (!isValid) break;
       if (successor.id == null) markInvalid("successor without id");
       if (successor.id <= block.id && !successor.isLoopHeader()) {
         markInvalid("successor with lower id, but not a loop-header");
@@ skipping 101 matching lines @@
       markInvalid("Instruction in wrong block");
     }
     if (!hasCorrectInputs()) {
       markInvalid("Incorrect inputs");
     }
     if (!hasCorrectUses()) {
       markInvalid("Incorrect uses");
     }
   }
 }