Avoid retaining reference to ProtoBuf.Package in JvmPackagePartSource

Otherwise, 2e933a165a doesn't help

core/descriptors.jvm/src/org/jetbrains/kotlin/load/kotlin/JvmPackagePartSource.kt

@@ -17,8 +17,11 @@
 package org.jetbrains.kotlin.load.kotlin
 
 import org.jetbrains.kotlin.descriptors.SourceFile
+import org.jetbrains.kotlin.load.java.JvmAbi
 import org.jetbrains.kotlin.metadata.ProtoBuf
 import org.jetbrains.kotlin.metadata.deserialization.NameResolver
+import org.jetbrains.kotlin.metadata.deserialization.getExtensionOrNull
+import org.jetbrains.kotlin.metadata.jvm.JvmProtoBuf
 import org.jetbrains.kotlin.name.ClassId
 import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.resolve.jvm.JvmClassName
@@ -28,8 +31,8 @@ import org.jetbrains.kotlin.serialization.deserialization.descriptors.Deserializ
 class JvmPackagePartSource(
     val className: JvmClassName,
     val facadeClassName: JvmClassName?,
-    val packageProto: ProtoBuf.Package,
-    val nameResolver: NameResolver,
+    packageProto: ProtoBuf.Package,
+    nameResolver: NameResolver,
     override val incompatibility: IncompatibleVersionErrorData<JvmMetadataVersion>? = null,
     override val isPreReleaseInvisible: Boolean = false,
     val knownJvmBinaryClass: KotlinJvmBinaryClass? = null
@@ -52,6 +55,10 @@ class JvmPackagePartSource(
         kotlinClass
     )
 
+    val moduleName =
+        packageProto.getExtensionOrNull(JvmProtoBuf.packageModuleName)?.let(nameResolver::getString)
+                ?: JvmAbi.DEFAULT_MODULE_NAME
+
     override val presentableString: String
         get() = "Class '${classId.asSingleFqName().asString()}'"