Remove hot assertion

We want this method to be a tiny as possible so it is
JVM inlined into call sites and free of any overhead.

Author: retronym

src/reflect/scala/reflect/internal/SymbolTable.scala

@@ -229,8 +229,6 @@ abstract class SymbolTable extends macros.Universe
   }
 
   final def phase_=(p: Phase): Unit = {
-    //System.out.println("setting phase to " + p)
-    assert((p ne null) && p != NoPhase, p)
     ph = p
     per = period(currentRunId, p.id)
   }