Remove DartString from constants.

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

Index: pkg/compiler/lib/src/inferrer/builder.dart
diff --git a/pkg/compiler/lib/src/inferrer/builder.dart b/pkg/compiler/lib/src/inferrer/builder.dart
index b9b7078c4849b2aad0b0e0d518d7b619bee8b2c2..d24d423c26e2a66594a190dd77224c83face4c13 100644
--- a/pkg/compiler/lib/src/inferrer/builder.dart
+++ b/pkg/compiler/lib/src/inferrer/builder.dart
@@ -207,7 +207,7 @@ class ElementGraphBuilder extends ast.Visitor<TypeInformation>
   }
 
   TypeInformation visitLiteralString(ast.LiteralString node) {
-    return types.stringLiteralType(node.dartString);
+    return types.stringLiteralType(node.dartString.slowToString());
   }
 
   TypeInformation visitStringJuxtaposition(ast.StringJuxtaposition node) {
@@ -216,7 +216,7 @@ class ElementGraphBuilder extends ast.Visitor<TypeInformation>
   }
 
   TypeInformation visitLiteralBool(ast.LiteralBool node) {
-    return types.boolLiteralType(node);
+    return types.boolLiteralType(node.value);
   }
 
   TypeInformation visitLiteralDouble(ast.LiteralDouble node) {