Fix for do/while: if there are phi copies after the condition, emit the non-pretty while loop.

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

 // Copyright (c) 2012, 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;
 
 abstract class HVisitor<R> {
   R visitAdd(HAdd node);
   R visitBailoutTarget(HBailoutTarget node);
   R visitBitAnd(HBitAnd node);
@@ skipping 2909 matching lines @@
     }
     return condition.start;
   }
 
   HBasicBlock get loopHeader {
     return kind == DO_WHILE_LOOP ? body.start : condition.start;
   }
 
   HBasicBlock get end {
     if (updates != null) return updates.end;
-    if (kind == DO_WHILE_LOOP) {
+    if (kind == DO_WHILE_LOOP && condition != null) {
       return condition.end;
     }
     return body.end;
   }
 
   static int loopType(Node node) {
     return node.accept(const LoopTypeVisitor());
   }
 
   bool accept(HStatementInformationVisitor visitor) =>
@@ skipping 74 matching lines @@
   HBasicBlock get start => expression.start;
   HBasicBlock get end {
     // We don't create a switch block if there are no cases.
     assert(!statements.isEmpty);
     return statements.last.end;
   }
 
   bool accept(HStatementInformationVisitor visitor) =>
       visitor.visitSwitchInfo(this);
 }