Cleanup and fixes to some dart:io files

runtime/bin/http_parser.dart

Index: runtime/bin/http_parser.dart
diff --git a/runtime/bin/http_parser.dart b/runtime/bin/http_parser.dart
index 14cc30d6ea4a2bf0de56774df769fb48866e85a0..2224e4b8716971efef2a71c5c902ae7004f49bed 100644
--- a/runtime/bin/http_parser.dart
+++ b/runtime/bin/http_parser.dart
@@ -533,7 +533,7 @@ class _HttpParser {
             index--;
             break;
 
-          case _state = _State.FAILURE:
+          case _State.FAILURE:
             // Should be unreachable.
             assert(false);
             break;
@@ -562,7 +562,7 @@ class _HttpParser {
     return index - offset;
   }
 
-  int connectionClosed() {
+  void connectionClosed() {
     if (_state < _State.FIRST_BODY_STATE) {
       _state = _State.FAILURE;
       // Report the error through the error callback if any. Otherwise
@@ -599,10 +599,8 @@ class _HttpParser {
     switch (_httpVersion) {
       case _HttpVersion.HTTP10:
         return "1.0";
-        break;
       case _HttpVersion.HTTP11:
         return "1.1";
-        break;
     }
     return null;
   }