dart2js: add FragmentEmitter for startup-emitter.

pkg/compiler/lib/src/js_emitter/startup_emitter/model_emitter.dart

Index: pkg/compiler/lib/src/js_emitter/startup_emitter/model_emitter.dart
diff --git a/pkg/compiler/lib/src/js_emitter/startup_emitter/model_emitter.dart b/pkg/compiler/lib/src/js_emitter/startup_emitter/model_emitter.dart
index 5048fe5f5cb7ea9024cd7c2a60ab652a034bcafa..9797dbb60f546d8fd3ce5080dd46d55ac10955cf 100644
--- a/pkg/compiler/lib/src/js_emitter/startup_emitter/model_emitter.dart
+++ b/pkg/compiler/lib/src/js_emitter/startup_emitter/model_emitter.dart
@@ -35,6 +35,8 @@ import 'package:js_runtime/shared/embedded_names.dart' show
 import '../js_emitter.dart' show NativeGenerator, buildTearOffCode;
 import '../model.dart';
 
+part 'fragment_emitter.dart';
+
 class ModelEmitter {
   final Compiler compiler;
   final Namer namer;
@@ -124,7 +126,55 @@ class ModelEmitter {
   }
 
   int emitProgram(Program program) {
-    // TODO(floitsch): implement.
-    throw new UnimplementedError("startup-emitter.emitProgram");
+    List<Fragment> fragments = program.fragments;
+    MainFragment mainFragment = fragments.first;
+
+    int totalSize = 0;
+
+    FragmentEmitter fragmentEmitter =
+        new FragmentEmitter(compiler, namer, backend, constantEmitter, this);
+
+    // We have to emit the deferred fragments first, since we need their
+    // deferred hash (which depends on the output) when emitting the main
+    // fragment.
+    List<js.Expression> fragmentsCode = fragments.skip(1).map(
+            (DeferredFragment deferredFragment) {
+          js.Expression types =
+          program.metadataTypesForOutputUnit(deferredFragment.outputUnit);
+          return fragmentEmitter.emitDeferredFragment(
+              deferredFragment, types, program.holders);
+        }).toList();
+
+    js.Statement mainAst = fragmentEmitter.emitMainFragment(program);
+
+    js.TokenCounter counter = new js.TokenCounter();
+    fragmentsCode.forEach(counter.countTokens);
+    counter.countTokens(mainAst);
+
+    program.finalizers.forEach((js.TokenFinalizer f) => f.finalizeTokens());
+
+    for (int i = 0; i < fragmentsCode.length; ++i) {
+      String code = js.prettyPrint(fragmentsCode[i], compiler).getText();
+      totalSize += code.length;
+      compiler.outputProvider(fragments[i+1].outputFileName, deferredExtension)
+        ..add(code)
+        ..close();
+    }
+
+    String mainCode = js.prettyPrint(mainAst, compiler).getText();
+    compiler.outputProvider(mainFragment.outputFileName, 'js')
+      ..add(buildGeneratedBy(compiler))
+      ..add(mainCode)
+      ..close();
+    totalSize += mainCode.length;
+
+    return totalSize;
+  }
+
+  String buildGeneratedBy(compiler) {
+    var suffix = '';
+    if (compiler.hasBuildId) suffix = ' version: ${compiler.buildId}';
+    return '// Generated by dart2js (fast startup), '
+        'the Dart to JavaScript compiler$suffix.\n';
   }
 }