Assignment expressions in tree IR.

pkg/compiler/lib/src/tree_ir/tree_ir_integrity.dart

Index: pkg/compiler/lib/src/tree_ir/tree_ir_integrity.dart
diff --git a/pkg/compiler/lib/src/tree_ir/tree_ir_integrity.dart b/pkg/compiler/lib/src/tree_ir/tree_ir_integrity.dart
index 8829e70d2d5875c252d265b02ee184cb703ac2f1..20225c932f89b0efb76ce4f5d9d1d4bceaae83ab 100644
--- a/pkg/compiler/lib/src/tree_ir/tree_ir_integrity.dart
+++ b/pkg/compiler/lib/src/tree_ir/tree_ir_integrity.dart
@@ -65,17 +65,16 @@ class CheckTreeIntegrity extends RecursiveVisitor {
     read(node.variable);
   }
 
-  visitAssign(Assign node) {
+  visitVariableDeclaration(VariableDeclaration node) {
     visitExpression(node.value);
-    if (node.isDeclaration) {
-      declare(node.variable);
-    } else {
-      write(node.variable);
-    }
+    declare(node.variable);
     visitStatement(node.next);
-    if (node.isDeclaration) {
-      undeclare(node.variable);
-    }
+    undeclare(node.variable);
+  }
+
+  visitAssign(Assign node) {
+    visitExpression(node.value);
+    write(node.variable);
   }
 
   visitTry(Try node) {