fix($compile): abort compilation when duplicate element transclusion

Issue an error and abort compilation when two directives that ask for transclusion are found
on a single element. This configuration is not supported and we previously failed to issue
the error because in the case of element transclusion the compilation is re-started and this
caused the compilation context to be lost.

The ngRepeat directive has been special-cased to bypass this warning because it knows how to
handle this scenario internally.

This is not an ideal solution to the problem of multiple transclusions per element, we are
hoping to have this configuration supported by the compiler in the future. See #4357.

Closes #3893
Closes #4217
Closes #3307