Wrap quill patched with Safari polyfill, add value property

[web-padawan]

Fixes #2

For now there are 2 main problems and both are related to the select controls:

• in Safari polyfilled selection does not apply
• in all the Shady DOM browers (Firefox 62, Edge, IE11) style scope does not apply

However, at least the normal button controls are confirmed to work. So let's start with something like that and consider a proper fix for select controls to be added later.

Note: PR includes a built Quill version with a patched polyfill. This should be suitable for MVP but we have to revisit it before 1.0.0 stable release.

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This change is 

[web-padawan]

Reviewable status: 0 of 5 files reviewed, 1 unresolved discussion

a discussion (no related file):
WIP, do not merge please. Blocking this PR to prevent merging by accident.

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[web-padawan]

This is now ready for review. Integrating Quill as a dependency is a subject to another discussion.

Reviewable status: 0 of 12 files reviewed, all discussions resolved

[web-padawan]

Note: changes to quill can be reviewed at slab/quill#2337

[yuriy-fix]

Not blockers:

• We can think about ways of setting Quill as the dependency, like it was described previously.

• We can try to implement our own lumo theme to be used instead of snow which brings quite a lot of non-clear css to the wc.

Reviewed 1 of 5 files at r1, 11 of 12 files at r2.
Reviewable status: all files reviewed, 2 unresolved discussions (waiting on @web-padawan)

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src/vaadin-rich-text-editor.html, line 108 at r2 (raw file):

            value: {
              type: Object,
              readOnly: true,

Should be writable.

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test/basic.html, line 151 at r2 (raw file):

        });

        it('should be read only and disallow modifications', () => {

Should be updated once value becomes writable.

[web-padawan]

Reviewable status: 10 of 12 files reviewed, 2 unresolved discussions (waiting on @YuriyVaadin)

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src/vaadin-rich-text-editor.html, line 108 at r2 (raw file):

Previously, YuriyVaadin (Yuriy Yevstihnyeyev) wrote…

Should be writable.

Done.

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test/basic.html, line 151 at r2 (raw file):

Previously, YuriyVaadin (Yuriy Yevstihnyeyev) wrote…

Should be updated once value becomes writable.

Done.

[yuriy-fix]

Reviewed 6 of 6 files at r3.
Reviewable status: complete! all files reviewed, all discussions resolved

[tomivirkki]

Reviewed 1 of 5 files at r1, 5 of 12 files at r2, 6 of 6 files at r3.
Reviewable status: complete! all files reviewed, all discussions resolved

[aadamsx]

This is now 100%? I can start using Quill in my LitElement components and still be in Shadow-DOM?

[tomivirkki]

@aadamsx We released version 1.0.0-alpha2 yesterday. Here's an example of it being used with lit element https://glitch.com/edit/#!/ritzy-bill