[Issue-2005] Don't prevent left arrow events on Break leafs

[MikaelCarpenter]

Links

• Initial issue report: Left key handler is not triggered in an empty editor #2005
• Relevant commit that added makeEmbedArrowHandler: link
• Issue that that commit was addressing: Two problems with InlineEmbed blot input #1635
• Codesandbox that illustrates the issues with ArrowLeft key bindings: link

Why

I'm currently trying to add a custom key binding for the left arrow. It works except for on empty lines (<p><br /></p>)

Description of the problem

• Keyboard has a default keybinding 'embed left' that is called before my custom key binding
• Currently 'embed left' is returning false when the cursor is in an instance of an EmbedBlot (code)
• My custom key binding is prevented based on the matches.some(...) logic (code)

What

• I updated the 'embed left' handler to ignore Break like it does for all other non EmbedBlots

Alternative Solutions

• Make the custom key bindings fire before the default ones
  • It seems as though custom key bindings are meant to fire before the default key bindings, if you pass them in as part of the config. However that doesn't seem to be the case anymore (see Codesandbox for how binding is added). So maybe the fix should be fore that instead?
• Alter the Break class to not inherit from EmbedBlot
  • I looked into this briefly and it seems like a much more complex change

Caveats

• I don't have a test for this, but I can add them once we can agree on a solution we want
  • i tested manually that my use case works as well as the use case that the original commit I referenced was trying to fix (using arrows to navigate past embeds like formulas)