Assignment expressions in tree IR.

pkg/compiler/lib/src/js_backend/codegen/codegen.dart

Index: pkg/compiler/lib/src/js_backend/codegen/codegen.dart
diff --git a/pkg/compiler/lib/src/js_backend/codegen/codegen.dart b/pkg/compiler/lib/src/js_backend/codegen/codegen.dart
index da111581ca403443c11e4acec84d2a09b83f3d32..125b1646f3949bd0b78d4849270491588bf75b2a 100644
--- a/pkg/compiler/lib/src/js_backend/codegen/codegen.dart
+++ b/pkg/compiler/lib/src/js_backend/codegen/codegen.dart
@@ -395,6 +395,13 @@ class CodeGenerator extends tree_ir.StatementVisitor
   }
 
   @override
+  js.Expression visitAssign(tree_ir.Assign node) {
+    return new js.Assignment(
+        buildVariableAccess(node.variable),
+        visitExpression(node.value));
+  }
+
+  @override
   void visitContinue(tree_ir.Continue node) {
     tree_ir.Statement fallthrough = this.fallthrough;
     if (node.target.binding == fallthrough) {
@@ -444,17 +451,6 @@ class CodeGenerator extends tree_ir.StatementVisitor
   }
 
   @override
-  void visitAssign(tree_ir.Assign node) {
-    tree_ir.Expression value = node.value;
-    js.Expression definition = visitExpression(value);
-
-    accumulator.add(new js.ExpressionStatement(new js.Assignment(
-        buildVariableAccess(node.variable),
-        definition)));
-    visitStatement(node.next);
-  }
-
-  @override
   void visitBreak(tree_ir.Break node) {
     tree_ir.Statement fallthrough = this.fallthrough;
     if (node.target.binding.next == fallthrough) {
@@ -560,14 +556,12 @@ class CodeGenerator extends tree_ir.StatementVisitor
   }
 
   @override
-  void visitSetField(tree_ir.SetField node) {
+  js.Assignment visitSetField(tree_ir.SetField node) {
     js.PropertyAccess field =
         new js.PropertyAccess.field(
             visitExpression(node.object),
             glue.instanceFieldPropertyName(node.field));
-    js.Assignment asn = new js.Assignment(field, visitExpression(node.value));
-    accumulator.add(new js.ExpressionStatement(asn));
-    visitStatement(node.next);
+    return new js.Assignment(field, visitExpression(node.value));
   }
 
   js.Expression buildStaticHelperInvocation(FunctionElement helper,
@@ -626,6 +620,11 @@ class CodeGenerator extends tree_ir.StatementVisitor
     return errorUnsupportedNode(node);
   }
 
+  @override
+  visitVariableDeclaration(tree_ir.VariableDeclaration node) {
+    return errorUnsupportedNode(node);
+  }
+
   errorUnsupportedNode(tree_ir.DartSpecificNode node) {
     throw "Unsupported node in JS backend: $node";
   }