Currently, the language service provides completions in a template node
attribute by first checking if the attribute contains template bindings
to provide completions for, and then providing completions for the
expression in the attribute.
In the latter case, the expression AST was being constructed
"synthetically" inside the language service, in particular declaring the
expression to be a `PropertyRead` with an implicit receiver.
Unfortunately, this AST can be incorrect if the expression is actually a
property read on a component property receiver (e.g. when reading
`key` in the expression `obj.key`, `obj` is the receiver).
The fix is pretty simple - rather than a synthetic construction of the
AST, ask the expression parser to parse the expression in the attribute.
Fixes https://github.com/angular/vscode-ng-language-service/issues/523
PR Close#34517
ee46b9b44f