Revert "add isIncremental method to PackageFragmentDescriptorImpl in order to recognize descriptors from incremental package fragments during compilation"

This reverts commit ddaebd2b27.

compiler/frontend.java/src/org/jetbrains/kotlin/load/kotlin/incremental/IncrementalPackageFragmentProvider.kt

@@ -134,8 +134,6 @@ public class IncrementalPackageFragmentProvider(
 
         override fun getMemberScope(): JetScope = memberScope()
 
-        override fun isIncremental(): Boolean = true
-
         private inner class IncrementalPackageScope(val packageData: PackageData) : DeserializedPackageMemberScope(
                 this@IncrementalPackageFragment, packageData.packageProto, packageData.nameResolver, deserializationComponents,
                 { listOf() }

core/descriptors/src/org/jetbrains/kotlin/descriptors/impl/PackageFragmentDescriptorImpl.kt

@@ -40,7 +40,4 @@ public abstract class PackageFragmentDescriptorImpl(
     }
 
     override fun toString(): String = "package $fqName"
-
-    @Deprecated("This is a hack in order to preliminary support internal visibility in multi-module projects")
-    open fun isIncremental(): Boolean = false
 }