Rich Text: Unrelated attributes are applied to Rich Text FormatType

[technote-space]

Describe the bug
There is an error in the program, which causes strange behavior as described in the title.

To reproduce

1. Register format type which has no attributes
   tagName: span, className: my-span (hereinafter referred to format type A)
2. Register format type which has style attribute
   e.g. install and activate Advanced Rich Text Tools for Gutenberg plugin
   https://wordpress.org/plugins/advanced-rich-text-tools/
   (e.g. background color)
   (hereinafter referred to format type B)
3. Input text and apply format type A to Rich Text on block editor
4. Apply format type B to Rich Text, which is

• same node as format type A
• prior to format type A
• not the beginning of the node

5. Clear format type B
   ⇒ the attributes that format type B had is applied to format type A
   (the attributes are not applied on the front end or after reloading editor)

Expected behavior
Unrelated attributes should not be applied.

Screenshots

Desktop (please complete the following information):

• OS: Windows10
• Browser:
  • ❌: Chrome (72.0.3626.121)
  • ❌: FireFox (65.0.2)
  • ✅: Edge (42.17134.1.0)
• Gutenberg plugin v5.1.0 ～ v5.4.0, WP5.2 beta1

Additional context
https://github.com/WordPress/gutenberg/blob/release/5.4/packages/rich-text/src/to-dom.js#L212

for ( let ii = 0; ii < currentAttributes.length; ii++ ) {
	const { name } = currentAttributes[ ii ];

	if ( ! futureChild.getAttribute( name ) ) {
		currentChild.removeAttribute( name );
	}
}

I think that it should be changed as shown below.

for ( let ii = currentAttributes.length; --ii >= 0; ) {
	const { name } = currentAttributes[ ii ];

	if ( ! futureChild.getAttribute( name ) ) {
		currentChild.removeAttribute( name );
	}
}

I tried the above changes locally and confirmed that they worked correctly.

• OS: Windows10
• Browser:
  • ✅: Chrome (72.0.3626.121)
  • ✅: FireFox (65.0.2)
  • ✅: Edge (42.17134.1.0)
• Gutenberg plugin v5.4.0

[youknowriad]

cc @ellatrix in case you have more info here.

[ellatrix]

@technote-space Thanks! Would you be able to make a PR with the suggested code change and perhaps a test case?

[technote-space]

I created PR #15070
Please review it.