Introduce boot.js: this finally makes it possible to load and run Todomvc

lib/src/html_css_fixup.dart

Index: lib/src/html_css_fixup.dart
diff --git a/lib/src/html_css_fixup.dart b/lib/src/html_css_fixup.dart
index e421b67a8cc056e354e23625e87b9fb4f77afc78..5f4cd2a3b41bad2e98090533227bdf1f6740469c 100644
--- a/lib/src/html_css_fixup.dart
+++ b/lib/src/html_css_fixup.dart
@@ -36,7 +36,9 @@ class CssPolyfillKind {
   static CssPolyfillKind of(CompilerOptions options, ComponentInfo component) {
     if (!options.processCss || !component.scoped) return NO_POLYFILL;
     if (options.mangleCss) return MANGLED_POLYFILL;
-    if (!component.hasAuthorStyles && !hasCssReset) return MANGLED_POLYFILL;
+    if (!component.hasAuthorStyles && options.resetCssFile == null) {
+      return MANGLED_POLYFILL;
+    }
     return SCOPED_POLYFILL;
   }
 }