fix: devtool select img element

[xxrlzzz]

Support select img element in chrome devtool

before:
https://github.com/openwebf/webf/assets/40893153/acfff80b-ba0f-4c08-90be-6d4200b55430

after:

after.mov

[andycall]

@xxrlzzz The CI reports lint errors:

Analyzing webf...                                               

   info • The import of 'rendering/root.dart' is unnecessary because all of the used elements are also provided by the import of 'package:webf/svg.dart' • lib/src/svg/svg.dart:12:8 • unnecessary_import
   info • The import of 'package:webf/src/svg/rendering/root.dart' is unnecessary because all of the used elements are also provided by the import of 'package:webf/svg.dart' 

[andycall]

[andycall]

../lib/src/rendering/box_model.dart:56:58: Error: Undefined name 'transform'.
      parentRenderer.applyLayoutTransform(childRenderer, transform, excludeScrollOffset);

[andycall]

@xxrlzzz You can try npm run lint to check that linter.

[xxrlzzz]

../lib/src/rendering/box_model.dart:56:58: Error: Undefined name 'transform'.
      parentRenderer.applyLayoutTransform(childRenderer, transform, excludeScrollOffset);

this line of code was introduced by 64cd037 , rather than this commit.

ci failed after commit fix: sliver layout child boundingClientRect offset error,

[andycall]

Fixed due to some changes conflict with other PR, please sync with main and try again.

[jinwencan]

lgtm