[FEATURE composable-computed-properties] Fix another CCP bug.

`normalizeDependentKey` had a typecheck, but it shouldn't really care about the
non-cp case.  More importantly, the typecheck didn't check for booleans so
things like `Em.computed.equal('isThisTypeCheckWorking', false)` would error.
Add Array.prototype.filter polyfill.

This is currently required (and only used by) the
composable-computed-properties feature. If that feature is enabled it
will not work in non-ES5 browsers (specifically it is not available in
IE8 and lower).
Merge pull request #4213 from rjackson/bring-back-array-filter-polyfil

Add Array.prototype.filter polyfill.
remove unneeded call in resolver, as we already have the correct this
Merge pull request #4209 from hjdivad/fix-ccp-stupid-typecheck

[FEATURE composable-computed-properties] Fix another CCP bug.