hyperscript: handles shared empty attrs, fixes #2821

[kfule]

Whenever there are selector-derived attrs, the attrs object will be regenerated and not shared.

Description

When selector-derived attrs exist, the attrs object is regenerated. However, if the attrs object is empty, the attrs object is not regenerated, and the selector-derived attrs is unintentionally shared.
In this pr, the condition !isEmpty(attrs) was removed so that even if the attrs object is empty, the attrs object is regenerated if there are selector-derived attrs.

Motivation and Context

One tiny bug #2821 has been fixed, and the code outlook is a bit better.

How Has This Been Tested?

Added test and ran npm run build.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation change

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.
• I have updated docs/changelog.md