Adds support for Razor templates and RenderFragment<T>.
Razor templates are a little-known Razor feature that looks like:
```
@<tag>....<tag>
```
It's so little known that it's not even covered in our docs, but it's
been around for many many years. This features hasn't been implemented
until now for Blazor, and this feature brings it back as a build
building block for templated components (more to come).
In Blazor land a template like:
```
@{ RenderFragment<Person> template = @<div>@item.Name</div>; }
```
complies to code like:
```
RenderFragment<Person> template = (__builder, item) =>
{
__builder.OpenElement(...);
...
__builder.CloseElement(...);
}
```
Since the declaration always has a generic type parameter inside, it
needs to be in a context where the type is known.. ie: not with `var`.
See tests for ways to consume templates.
NOTE: There are the following caveats for templates
- Templates require a single root element.
- Templates don't work in the `@functions { }` block
These limitations are baked into the core of Razor and will take a while
for us to address (v3.0).
* Reenable HtmlBlock unit tests
* Add E2E tests for HTML Block cases
* Remove harded GenerateBaselines=true
* Fix#1193
This commit addresses the root cause of #1193. When we merge HTML
text nodes into HTML blocks we need to re-encode any HTML entities that
were encoded eariler.
I did a bit of a deep dive on how HTML encoding is handled in Blazor and
I think this is the best strategy. I think it's valuable that the
BrowserRenderer uses document.createTextNode, which will always encode
the text - this handles dynamic content. We want to keep this in place
to avoid HTML injection attacks.
* Fix#1265 Reenable MarkupBlock
* test cleanup
* Add HTML Block rewriter
* Baseline updates
* test gaps
* Update some unit tests to represent same behavior as before
* Define Markup frame type. Tests for rendering markup frames into render tree.
* Support markup frames during diffing (retain, insert, update, delete)
* Support markup blocks on WebAssembly
* Support rendering markup frames with server-side execution too
* Support markup blocks with multiple top-level nodes. Support updating markup dynamically.
* Define MarkupString type as a way to insert dynamic markup without needing custom RenderFragment code
* Remove comment
* CR: Better null value handling
Ryan Nowak
Steve Sanderson