Revert "feat(compiler): support ScopeAware for decorators"

This reverts commit 9659dd1721c8011bd26d1855ca268a967805c4e2.

Wrong version of this PR was added in master, correct version is in
g3v1x.
feat(compiler): support ScopeAware for decorators

Even though decorators can safely inject scope (even after the proposed
context change), they might pick up ScopeAware from a base class shared
with components. Instead of manually calling super.scope = scope, we
support ScopeAware for decorators (similarly to Attach/DetachAware.)

There is no performance reduction on the tree benchmark.
chore(introspection): clean up workarounds for dart 1.4 and 1.5
fix(scope): fix a potential memory leak
perf(view): increase view instantiation speed 40%

1) Stop using futures when the value is already cached
2) Remove adding nodes to fake parent during view instantiation

Closes #1358
refactor(DirectiveInjector): better var names and comments
feat(scope): component is the new context

BREAKING CHANGE:

Scope context is set to the component instance that trigged the creation
of the scope (previously it was of a PrototypeMap.)

Repercussions:
1) You can not inject a scope in a component or in the root context any
more.

As the Scope context is set to the Component instance, the scope could
not be injected any more. Components should implements the "ScopeAware"
interface and declare a "scope" setter in order to get a reference to
the scope.

before:

     @Component(...)
     class MyComponent {
       Watch watch;
       Scope scope;

       MyComponent(Dependency myDep, Scope scope) {
          watch = scope.rootScope.watch("expression", (v, p) => ...);
       }
     }

after:

     @Component(...)
     class MyComponent implements ScopeAware {
       Watch watch;

       MyComponent(Dependency myDep) {
         // It is an error to add a Scope argument to the
         // ctor and will result in a DI circular dependency error
         // The scope is never accessible in the class constructor
       }

       void set scope(Scope scope) {
          // This setter gets called to initialize the scope
          watch = scope.watch("expression", (v, p) => ...);
       }
     }

or:

     @Component(...)
     class MyComponent implements ScopeAware {
       Scope scope;

       MyComponent(Dependency myDep) {
         // It is an error to add a Scope argument to the
         // ctor and will result in a DI circular dependency error
         // The scope is never accessible in the class constructor
       }
     }

2) The parent component to an NgForm must have a "$name" field to store
   the form instance.

closes #919
closes #917