v0.900.6

This release upgrades @angular/language-service to v9.0.0-rc.10.
For a complete change log see here.

It also upgrades vscode-languageclient and vscode-languageserver to major
version 6.

New features:

• Completions support for template reference variables
• Provide completion for $event variable
• Support hover/definitions for structural directive
• Add grammar for template bindings