kernel->ssa: implement for-in loops

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

Index: pkg/compiler/lib/src/ssa/builder.dart
diff --git a/pkg/compiler/lib/src/ssa/builder.dart b/pkg/compiler/lib/src/ssa/builder.dart
index a39f87cd0154b3f5c73a113ea423ff76ffc08483..a980869a9c1fdf33cbe22c05b0bcf4bfa9730b1a 100644
--- a/pkg/compiler/lib/src/ssa/builder.dart
+++ b/pkg/compiler/lib/src/ssa/builder.dart
@@ -48,23 +48,6 @@ import 'optimize.dart';
 import 'ssa_branch_builder.dart';
 import 'types.dart';
 
-/// A synthetic local variable only used with the SSA graph.
-///
-/// For instance used for holding return value of function or the exception of a
-/// try-catch statement.
-class SyntheticLocal extends Local {
-  final String name;
-  final ExecutableElement executableContext;
-
-  // Avoid slow Object.hashCode.
-  final int hashCode = _nextHashCode = (_nextHashCode + 1).toUnsigned(30);
-  static int _nextHashCode = 0;
-
-  SyntheticLocal(this.name, this.executableContext);
-
-  toString() => 'SyntheticLocal($name)';
-}
-
 class SsaBuilderTask extends CompilerTask {
   final CodeEmitterTask emitter;
   final JavaScriptBackend backend;
@@ -5652,7 +5635,7 @@ class SsaBuilder extends ast.Visitor
 
     // This scheme recognizes for-in on direct lists.  It does not recognize all
     // uses of ArrayIterator.  They still occur when the receiver is an Iterable
-    // with a `get iterator` method that delegate to another Iterable and the
+    // with a `get iterator` method that delegates to another Iterable and the
     // method is inlined.  We would require full scalar replacement in that
     // case.