Commit 53fc2ed8bf added support for
determining index types accessed using index signatures, but did not
include support for index types accessed using dot notation:
```typescript
const obj<T>: { [key: string]: T };
obj['stringKey']. // gets `T.` completions
obj.stringKey. // did not peviously get `T.` completions
```
This adds support for determining an index type accessed via dot
notation by rigging an object's symbol table to return the string index
signature type a property access refers to, if that property does not
explicitly exist on the object. This is very similar to @ivanwonder's
work in #29811.
`SymbolWrapper` now takes an additional parameter to explicitly set the
type of the symbol wrapped. This is done because
`SymbolTableWrapper#get` only has access to the symbol of the index
type, _not_ the index signature symbol itself. An attempt to get the
type of the index type will give an error.
Closes#29811
Closes https://github.com/angular/vscode-ng-language-service/issues/126
PR Close#33884
49804fe017