make SCHEMAS extendable

[zh99998]

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[x] feature request
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Current behavior

now schemas are not extendable, only hard-coded CUSTOM_ELEMENT_SCHEMA and NO_ERRORS_SCHEMA available. if a user want to add new schema, they have to modify DomElementSchemaRegistry.hasElement,DomElementSchemaRegistry.prototype.hasProperty or other compiler methods to do it. like this
https://github.com/moecube/electron-schema/blob/master/index.ts

Expected behavior

angular/packages/compiler/src/schema/dom_element_schema_registry.ts

Line 287 in 5b141fb

if (schemaMetas.some((schema) => schema.name === NO_ERRORS_SCHEMA.name)) {

make DomElementSchemaRegistry.hasElement,DomElementSchemaRegistry.prototype.hasProperty and other compiler methods to read schemaMetas not only name, but also some contents, for example, a string[] like SCHEMA defined in

angular/packages/compiler/src/schema/dom_element_schema_registry.ts

Line 79 in 5b141fb

const SCHEMA:

then user can just declare something like

const ELECTRON_SCHEMA = ['webview^[HTMLElement]|src,...']

then put it in ngModule.schemas .

@NgModule({
  // ...
  schemas: [ELECTRON_SCHEMA]
})
export class AppModule {
}

for more clearly, it could be a interface rather than a string, like..

interface SchemaData {
  tagName: string
  type: string
  attributes: string[]
  ... // other security-related fields
}

for more dynamic use, it could also be a function-based interface, it can combined with normal SchemaMetadata interface, for example:

interface SchemaMeta {
  name: string
  hasElement?(tagName, schemaMetas): boolean
  hasProperty?(tagName, propName, schemaMetas): boolean
  ... // other security-related methods
}

then CUSTOM_ELEMENTS_SCHEMA and NO_ERROES_SCHEMA could also be a normal SchemaMeta, and don't need hard-code in compiler, like

class NO_ERROES_SCHEMA implements SchemaMetadata {
  name: 'no-errors-schema'
  hasElement(tagName, schemaMetas) {return true}
  hasProperty(tagName, propName, schemaMetas) {return true}
}

[vicb]

Duplicate of #12045

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