Implement modular compilation

test/codegen/expect/dir/html_input_d.js

Index: test/codegen/expect/dir/html_input_d.js
diff --git a/test/codegen/expect/dir/html_input_d.js b/test/codegen/expect/dir/html_input_d.js
deleted file mode 100644
index debfbdae9bbed2fd7fffca619d613e2a88edae9d..0000000000000000000000000000000000000000
--- a/test/codegen/expect/dir/html_input_d.js
+++ /dev/null
@@ -1,14 +0,0 @@
-dart_library.library('dir/html_input_d', null, /* Imports */[
-  'dart/_runtime',
-  'dart/core'
-], /* Lazy imports */[
-], function(exports, dart, core) {
-  'use strict';
-  let dartx = dart.dartx;
-  function fib(n) {
-    return n == 0 || n == 1 ? 1 : dart.notNull(fib(dart.notNull(n) - 1)) + dart.notNull(fib(dart.notNull(n) - 2));
-  }
-  dart.fn(fib, core.int, [core.int]);
-  // Exports:
-  exports.fib = fib;
-});