Fix invalid SSA graph generated by dart2js by using the savedLocals in a do/while (the ones before …

sdk/lib/_internal/compiler/implementation/ssa/builder.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;
 
 /**
  * A special element for the extra parameter taken by intercepted
  * methods. We need to override [Element.computeType] because our
  * optimizers may look at its declared type.
@@ skipping 592 matching lines @@
    * exclude local values from the result when they are no longer in scope.
    */
   LocalsHandler mergeMultiple(List<LocalsHandler> localsHandlers,
                               HBasicBlock joinBlock) {
     assert(localsHandlers.length > 0);
     if (localsHandlers.length == 1) return localsHandlers[0];
     Map<Element, HInstruction> joinedLocals =
         new LinkedHashMap<Element,HInstruction>();
     HInstruction thisValue = null;
     directLocals.forEach((Element element, HInstruction instruction) {
-      if (!identical(element, closureData.thisElement)) {
+      if (element != closureData.thisElement) {
         HPhi phi = new HPhi.noInputs(element);
         joinedLocals[element] = phi;
         joinBlock.addPhi(phi);
       } else {
         // We know that "this" never changes, if it's there.
         // Save it for later. While merging, there is no phi for "this",
         // so we don't have to special case it in the merge loop.
         thisValue = instruction;
       }
     });
     for (LocalsHandler handler in localsHandlers) {
       handler.directLocals.forEach((Element element, HInstruction instruction) {
         HPhi phi = joinedLocals[element];
         if (phi != null) {
           phi.addInput(instruction);
         }
       });
     }
     if (thisValue != null) {
       // If there was a "this" for the scope, add it to the new locals.
       joinedLocals[closureData.thisElement] = thisValue;
     }
-    directLocals = joinedLocals;
+
+    // Remove locals that are not in all handlers.
+    directLocals = new LinkedHashMap<Element, HInstruction>();
+    joinedLocals.forEach((element, instruction) {
+      if (instruction is HPhi
+          && instruction.inputs.length != localsHandlers.length) {
+        joinBlock.removePhi(instruction);
+      } else {
+        directLocals[element] = instruction;
+      }
+    });
     return this;
   }
 }
 
 
 // Represents a single break/continue instruction.
 class JumpHandlerEntry {
   final HJump jumpInstruction;
   final LocalsHandler locals;
   bool isBreak() => jumpInstruction is HBreak;
@@ skipping 4557 matching lines @@
           new HSubGraphBlockInformation(elseBranch.graph));
 
     HBasicBlock conditionStartBlock = conditionBranch.block;
     conditionStartBlock.setBlockFlow(info, joinBlock);
     SubGraph conditionGraph = conditionBranch.graph;
     HIf branch = conditionGraph.end.last;
     assert(branch is HIf);
     branch.blockInformation = conditionStartBlock.blockFlow;
   }
 }