Multiple type applications on overloaded method crashes dotc, and different behavior from scalac

[Jasper-M]

Inspired by scala/bug#10628.

I'm not sure if I should create 2 separate issues or not, so apologies in advance.

The following invalid code:

object A {
  def a[F](x: Int) = 0
  def a[F](x: String) = 0
}
A.a[Int][String](0)

crashes the compiler with:

java.lang.AssertionError: assertion failed
	at scala.Predef$.assert(Predef.scala:204)
	at dotty.tools.dotc.typer.Applications.$anonfun$resolveOverloaded$5(Applications.scala:1390)
	at dotty.tools.dotc.util.Stats$.track(Stats.scala:35)
	at dotty.tools.dotc.typer.Applications.resolveOverloaded(Applications.scala:1303)
	at dotty.tools.dotc.typer.Applications.$anonfun$resolveOverloaded$5(Applications.scala:1392)
	at dotty.tools.dotc.util.Stats$.track(Stats.scala:35)
	at dotty.tools.dotc.typer.Applications.resolveOverloaded(Applications.scala:1303)
	at dotty.tools.dotc.typer.Applications.$anonfun$resolveOverloaded$1(Applications.scala:1289)
	at dotty.tools.dotc.util.Stats$.track(Stats.scala:35)
	at dotty.tools.dotc.typer.Applications.resolveOverloaded(Applications.scala:1244)
	at dotty.tools.dotc.typer.Applications.resolveOverloaded$(Applications.scala:1244)
	at dotty.tools.dotc.typer.Typer.resolveOverloaded(Typer.scala:82)
	at dotty.tools.dotc.typer.Typer.adaptOverloaded$1(Typer.scala:2019)
	at dotty.tools.dotc.typer.Typer.adaptInterpolated(Typer.scala:2417)
	at dotty.tools.dotc.typer.Typer.$anonfun$adapt$3(Typer.scala:1962)
	at dotty.tools.dotc.reporting.trace$.op1$2(trace.scala:25)
	at dotty.tools.dotc.reporting.trace$.apply(trace.scala:26)
	at dotty.tools.dotc.typer.Typer.$anonfun$adapt$1(Typer.scala:1955)
	at dotty.tools.dotc.util.Stats$.track(Stats.scala:35)
	at dotty.tools.dotc.typer.Typer.adapt(Typer.scala:1955)
	at dotty.tools.dotc.typer.Typer.$anonfun$typed$2(Typer.scala:1790)
	at dotty.tools.dotc.reporting.trace$.op1$2(trace.scala:25)
	at dotty.tools.dotc.reporting.trace$.apply(trace.scala:26)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:1786)
	at dotty.tools.dotc.typer.Typer.typedExpr(Typer.scala:1847)
	at dotty.tools.dotc.typer.Applications.$anonfun$typedTypeApply$1(Applications.scala:792)
	at dotty.tools.dotc.util.Stats$.track(Stats.scala:35)
	at dotty.tools.dotc.typer.Applications.typedTypeApply(Applications.scala:789)
	at dotty.tools.dotc.typer.Applications.typedTypeApply$(Applications.scala:789)
	at dotty.tools.dotc.typer.Typer.typedTypeApply(Typer.scala:82)
        ...

The same for the following valid code:

class Apply { def apply[A](x: Int) = 1 } 
object A {
  def a[F] = new Apply
  def a[F](x: String) = 0
} 
A.a[String][Int](3)

Also, given the previous definitions of Apply and A, the following doesn't compile with dotc but does with scalac:

A.a[String](3) // scala 2.12.4 returns 1