Stop working around issue 6775.

sdk/lib/_internal/pub/lib/src/http.dart

Index: sdk/lib/_internal/pub/lib/src/http.dart
diff --git a/sdk/lib/_internal/pub/lib/src/http.dart b/sdk/lib/_internal/pub/lib/src/http.dart
index b23dfd0e5a20292a38fd704d3ce270021076882b..a54f02f26ae0897790e5f9c5b48788366c4709ad 100644
--- a/sdk/lib/_internal/pub/lib/src/http.dart
+++ b/sdk/lib/_internal/pub/lib/src/http.dart
@@ -204,8 +204,7 @@ Map parseJsonResponse(http.Response response) {
   var value;
   try {
     value = json.parse(response.body);
-  } catch (e) {
-    // TODO(nweiz): narrow this catch clause once issue 6775 is fixed.
+  } on FormatException catch (e) {
     invalidServerResponse(response);
   }
   if (value is! Map) invalidServerResponse(response);