Introduce "platform configurations" to replace categories and libraries.dart.

pkg/dart2js_incremental/lib/dart2js_incremental.dart

Index: pkg/dart2js_incremental/lib/dart2js_incremental.dart
diff --git a/pkg/dart2js_incremental/lib/dart2js_incremental.dart b/pkg/dart2js_incremental/lib/dart2js_incremental.dart
index a03829defa98d690f5d6b1e004f81e7c2a657010..1ce8039c6b68ec836f1aa0f9e6b25060b73833b9 100644
--- a/pkg/dart2js_incremental/lib/dart2js_incremental.dart
+++ b/pkg/dart2js_incremental/lib/dart2js_incremental.dart
@@ -124,7 +124,7 @@ class IncrementalCompiler {
     }
     Future mappingInputProvider(Uri uri) {
       Uri updatedFile = updatedFiles[uri];
-      return inputProvider(updatedFile == null ? uri : updatedFile);
+      return inputProvider.readFromUri(updatedFile == null ? uri : updatedFile);
     }
     LibraryUpdater updater = new LibraryUpdater(
         _compiler,
@@ -134,7 +134,7 @@ class IncrementalCompiler {
         _context);
     _context.registerUriWithUpdates(updatedFiles.keys);
     Future<CompilerImpl> future = _reuseCompiler(updater.reuseLibrary);
-    return future.then((Compiler compiler) {
+    return future.then((CompilerImpl compiler) {
       _compiler = compiler;
       if (compiler.compilationFailed) {
         return null;
@@ -157,9 +157,7 @@ function dartMainRunner(main, args) {
   return main(args);
 }""", {'updates': updates, 'helper': backend.namer.accessIncrementalHelper});
 
-    jsAst.Printer printer = new jsAst.Printer(_compiler, null);
-    printer.blockOutWithoutBraces(mainRunner);
-    return printer.outBuffer.getText();
+    return jsAst.prettyPrint(mainRunner, _compiler).getText();
   }
 }