When binding an array to `class` like `[class]="['foo', 'bar']"`, the runtime treats it the same as a literal binding with all the values being `true`, e.g. `{foo: true, bar: true}`. While object literals can only have string keys, arrays can have any value which can lead to errors if the array contains non-string values.
These changes add some logic to stringify the keys and ignore invalid ones.
Fixes#48473.
PR Close#49924
Kristiyan Kostadinov
2fff8fadbe