Add platform/impl soft keywords, add isPlatform/isImpl to MemberDescriptor

core/deserialization/src/org/jetbrains/kotlin/serialization/deserialization/NotFoundClasses.kt

@@ -100,6 +100,8 @@ class NotFoundClasses(private val storageManager: StorageManager, private val mo
 
         override fun isCompanionObject() = false
         override fun isData() = false
+        override fun isPlatform() = false
+        override fun isImpl() = false
         override val annotations: Annotations get() = Annotations.EMPTY
 
         override fun getUnsubstitutedMemberScope() = MemberScope.Empty

core/deserialization/src/org/jetbrains/kotlin/serialization/deserialization/descriptors/DeserializedClassDescriptor.kt

@@ -95,6 +95,10 @@ class DeserializedClassDescriptor(
 
     override fun isData() = Flags.IS_DATA.get(classProto.flags)
 
+    override fun isPlatform() = false
+
+    override fun isImpl() = false
+
     override fun getUnsubstitutedMemberScope(): MemberScope = memberScope
 
     override fun getStaticScope() = staticScope