Implement modular compilation

lib/runtime/dart/_metadata.js

-dart_library.library('dart/_metadata', null, /* Imports */[
-  'dart/_runtime',
-  'dart/core'
-], /* Lazy imports */[
-], function(exports, dart, core) {
-  'use strict';
-  let dartx = dart.dartx;
-  class SupportedBrowser extends core.Object {
-    SupportedBrowser(browserName, minimumVersion) {
-      if (minimumVersion === void 0) minimumVersion = null;
-      this.browserName = browserName;
-      this.minimumVersion = minimumVersion;
-    }
-  }
-  dart.setSignature(SupportedBrowser, {
-    constructors: () => ({SupportedBrowser: [SupportedBrowser, [core.String], [core.String]]})
-  });
-  SupportedBrowser.CHROME = "Chrome";
-  SupportedBrowser.FIREFOX = "Firefox";
-  SupportedBrowser.IE = "Internet Explorer";
-  SupportedBrowser.OPERA = "Opera";
-  SupportedBrowser.SAFARI = "Safari";
-  class Experimental extends core.Object {
-    Experimental() {
-    }
-  }
-  dart.setSignature(Experimental, {
-    constructors: () => ({Experimental: [Experimental, []]})
-  });
-  class DomName extends core.Object {
-    DomName(name) {
-      this.name = name;
-    }
-  }
-  dart.setSignature(DomName, {
-    constructors: () => ({DomName: [DomName, [core.String]]})
-  });
-  class DocsEditable extends core.Object {
-    DocsEditable() {
-    }
-  }
-  dart.setSignature(DocsEditable, {
-    constructors: () => ({DocsEditable: [DocsEditable, []]})
-  });
-  class Unstable extends core.Object {
-    Unstable() {
-    }
-  }
-  dart.setSignature(Unstable, {
-    constructors: () => ({Unstable: [Unstable, []]})
-  });
-  // Exports:
-  exports.SupportedBrowser = SupportedBrowser;
-  exports.Experimental = Experimental;
-  exports.DomName = DomName;
-  exports.DocsEditable = DocsEditable;
-  exports.Unstable = Unstable;
-});