dump-info additionally dumps a json info file

sdk/lib/_internal/compiler/implementation/dart2js.dart

Index: sdk/lib/_internal/compiler/implementation/dart2js.dart
diff --git a/sdk/lib/_internal/compiler/implementation/dart2js.dart b/sdk/lib/_internal/compiler/implementation/dart2js.dart
index 583c268468beaeb08a30a2f056a9f2b59c0260ee..8229407b4b112d2a46b17e2292d1db7f9fc1398b 100644
--- a/sdk/lib/_internal/compiler/implementation/dart2js.dart
+++ b/sdk/lib/_internal/compiler/implementation/dart2js.dart
@@ -418,9 +418,9 @@ Future compile(List<String> argv) {
             " \"Content-Security-Policy: script-src 'self'\"");
       } else if (extension == 'js.map' || extension == 'dart.map') {
         uri = sourceMapOut;
-      } else if (extension == 'info.html') {
+      } else if (extension == 'info.html' || extension == "info.json") {
         String outName = out.path.substring(out.path.lastIndexOf('/') + 1);
-        uri = out.resolve('${outName}.$extension');
+        uri = out.resolve('$outName.$extension');
       } else {
         fail('Unknown extension: $extension');
       }