feat(block): Chain ElementProbe parents; add to shadowRoot

This allows one to retrieve ElementProbe from any element including
a shadowRoot. The ElementProbe contains element, injector, and scope. 
The added benefit is that by waling the ElementProbe parent one can 
get the parent element of a shadow DOM.

Closes #625
Closes #630
refactor(specs): main() does not return a value (void)

closes #627
perf(scope): optim createChild() which always append at the end

Closes #626
chore(pubspec): set sdk requirement to 1.2.0+
chore(pubspec.lock): update pubspec.lock
refactor(parser): remove hacks and just use instanceMembers