fail slightly later when scala.runtime.Lazy* is missing

Author: adriaanm

src/reflect/scala/reflect/internal/Definitions.scala

@@ -93,9 +93,9 @@ trait Definitions extends api.StandardDefinitions {
     lazy val boxedClass       = classesMap(x => getClassByName(boxedName(x)))
     lazy val refClass         = classesMap(x => getRequiredClass("scala.runtime." + x + "Ref"))
     lazy val volatileRefClass = classesMap(x => getRequiredClass("scala.runtime.Volatile" + x + "Ref"))
-    lazy val lazyHolders      = symbolsMap(ScalaValueClasses, x => getRequiredClass("scala.runtime.Lazy" + x))
-    lazy val LazyRefClass     = getRequiredClass("scala.runtime.LazyRef")
-    lazy val LazyUnitClass    = getRequiredClass("scala.runtime.LazyUnit")
+    lazy val lazyHolders      = symbolsMap(ScalaValueClasses, x => getClassIfDefined("scala.runtime.Lazy" + x))
+    lazy val LazyRefClass     = getClassIfDefined("scala.runtime.LazyRef")
+    lazy val LazyUnitClass    = getClassIfDefined("scala.runtime.LazyUnit")
 
     lazy val allRefClasses: Set[Symbol] = {
       refClass.values.toSet ++ volatileRefClass.values.toSet ++ Set(VolatileObjectRefClass, ObjectRefClass)