Partially Revert "Fix wrong calculation of generic params per level when building decl"

(Keeps the test, but reverts the code changes; the test will be updated later.)

This reverts most of commit 893d83b from PR #62854

Author: tbkka

include/swift/Remote/MetadataReader.h

@@ -2959,19 +2959,13 @@ class MetadataReader {
           // Only consider generic contexts of type class, enum or struct.
           // There are other context types that can be generic, but they should
           // not affect the generic shape.
-          if (current->getKind() == ContextDescriptorKind::Class ||
-              current->getKind() == ContextDescriptorKind::Enum ||
-              current->getKind() == ContextDescriptorKind::Struct) {
-            if (genericContext) {
-              auto contextHeader = genericContext->getGenericContextHeader();
-              paramsPerLevel.emplace_back(contextHeader.NumParams -
-                                          runningCount);
-              runningCount += paramsPerLevel.back();
-            } else {
-              // If there is no generic context, this is a non-generic type
-              // which has 0 generic parameters.
-              paramsPerLevel.emplace_back(0);
-            }
+          if (genericContext &&
+              (current->getKind() == ContextDescriptorKind::Class ||
+               current->getKind() == ContextDescriptorKind::Enum ||
+               current->getKind() == ContextDescriptorKind::Struct)) {
+            auto contextHeader = genericContext->getGenericContextHeader();
+            paramsPerLevel.emplace_back(contextHeader.NumParams - runningCount);
+            runningCount += paramsPerLevel.back();
           }
         };
     countLevels(descriptor, runningCount);

include/swift/RemoteInspection/TypeRefBuilder.h

@@ -615,13 +615,9 @@ class TypeRefBuilder {
           break;
         }
       }
-      if (parentNode) {
-        if (shapeIndex > 0)
-          parent = createBoundGenericTypeReconstructingParent(
-              parentNode, decl, --shapeIndex, args, argsIndex + numGenericArgs);
-        else
-          return nullptr;
-      }
+      if (parentNode)
+        parent = createBoundGenericTypeReconstructingParent(
+            parentNode, decl, --shapeIndex, args, argsIndex + numGenericArgs);
     }
 
     return BoundGenericTypeRef::create(*this, mangling.result(), genericParams,