Finish strong mode cleaning of dart2js.

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

Index: pkg/compiler/lib/src/ssa/optimize.dart
diff --git a/pkg/compiler/lib/src/ssa/optimize.dart b/pkg/compiler/lib/src/ssa/optimize.dart
index b4a059b286d4761d57ce362392f18afde944994c..ccf7f1eff5a6886227b34725750bf9213d7c50db 100644
--- a/pkg/compiler/lib/src/ssa/optimize.dart
+++ b/pkg/compiler/lib/src/ssa/optimize.dart
@@ -923,7 +923,7 @@ class SsaInstructionSimplifier extends HBaseVisitor
   }
 
   HInstruction visitGetLength(HGetLength node) {
-    var receiver = node.receiver;
+    dynamic receiver = node.receiver;
     if (_graph.allocatedFixedLists.contains(receiver)) {
       // TODO(ngeoffray): checking if the second input is an integer
       // should not be necessary but it currently makes it easier for
@@ -935,7 +935,7 @@ class SsaInstructionSimplifier extends HBaseVisitor
     } else if (receiver.isConstantList() || receiver.isConstantString()) {
       return _graph.addConstantInt(receiver.constant.length, _closedWorld);
     } else {
-      var type = receiver.instructionType;
+      dynamic type = receiver.instructionType;
       if (type.isContainer && type.length != null) {
         HInstruction constant =
             _graph.addConstantInt(type.length, _closedWorld);
@@ -963,7 +963,7 @@ class SsaInstructionSimplifier extends HBaseVisitor
 
   HInstruction visitIndex(HIndex node) {
     if (node.receiver.isConstantList() && node.index.isConstantInteger()) {
-      var instruction = node.receiver;
+      dynamic instruction = node.receiver;
       List<ConstantValue> entries = instruction.constant.entries;
       instruction = node.index;
       int index = instruction.constant.primitiveValue;