Support local variables in dart2dart.

sdk/lib/_internal/compiler/implementation/ir/ir_builder.dart

Index: sdk/lib/_internal/compiler/implementation/ir/ir_builder.dart
diff --git a/sdk/lib/_internal/compiler/implementation/ir/ir_builder.dart b/sdk/lib/_internal/compiler/implementation/ir/ir_builder.dart
index 7057a5504a20b48230475302e44b897bf3a0e5eb..5dda57843d7958316e2e1de85a56e703c2d9086c 100644
--- a/sdk/lib/_internal/compiler/implementation/ir/ir_builder.dart
+++ b/sdk/lib/_internal/compiler/implementation/ir/ir_builder.dart
@@ -419,12 +419,39 @@ class IrBuilder extends ResolvedVisitor<ir.Definition> {
     if (!Elements.isLocal(element)) return giveup();
     if (node.assignmentOperator.source != '=') return giveup();
     // Exactly one argument expected for a simple assignment.
-    assert(!node.arguments.isEmpty && node.arguments.tail.isEmpty);
+    assert(!node.arguments.isEmpty);
+    assert(node.arguments.tail.isEmpty);
     ir.Definition result = node.arguments.head.accept(this);
     assignedVars[variableIndex[element]] = result;
     return result;
   }
 
+  ir.Definition visitVariableDefinitions(ast.VariableDefinitions node) {
+    assert(isOpen);
+    for (ast.Node definition in node.definitions.nodes) {
+      Element element = elements[definition];
+      // Definitions are either SendSets if there is an initializer, or
+      // Identifiers if there is no initializer.
+      if (definition is ast.SendSet) {
+        assert(!definition.arguments.isEmpty);
+        assert(definition.arguments.tail.isEmpty);
+        ir.Definition initialValue = definition.arguments.head.accept(this);
+        if (!isOpen) return null;

[karlklose, 2014/04/11 09:01:56]

Perhaps add a comment.

[Kevin Millikin (Google), 2014/04/11 10:28:51]

I will.

+        variableIndex[element] = assignedVars.length;
+        assignedVars.add(initialValue);
+      } else {
+        assert(definition is ast.Identifier);
+        // The initial value is null.
+        // TODO(kmillikin): Consider pooling constants.
+        ir.Constant constant = new ir.Constant(constantSystem.createNull());
+        add(new ir.LetPrim(constant));
+        variableIndex[element] = assignedVars.length;
+        assignedVars.add(constant);
+      }
+    }
+    return null;
+  }
+
   static final String ABORT_IRNODE_BUILDER = "IrNode builder aborted";
 
   ir.Definition giveup() => throw ABORT_IRNODE_BUILDER;