fix(ngModel): test & update correct model when running $validate

If `$validate` is invoked when the model is already invalid, `$validate`
should pass `$$invalidModelValue` to the validators, not `$modelValue`.

Moreover, if `$validate` is invoked and it is found that the invalid model
has become valid, this previously invalid model should be assigned to
`$modelValue`.

Lastly, if `$validate` is invoked and it is found that the model has
become invalid, the previously valid model should be assigned to
`$$invalidModelValue`.

Closes #7836
Closes #7837
test(input): simplified $apply syntax
docs(error/$rootScope/inprog): fix $timeout typo

Closes #8071
fix(parseKeyValue): ignore properties in prototype chain.

Previously, properties (typically functions) in the prototype chain (Object.prototype) would shadow
query parameters, and cause them to be serialized incorrectly.

This CL guards against this by using hasOwnProperty() to ensure that only own properties are a concern.

Fixes #8068