[lldb] TSSTypeRef::GetBitSize fallback to SASTContext if runtime fails

The usual strategy of TypeSystemSwiftTypeRef functions is to fallback to
SwiftASTContext in case it fails, make GetBitSize follow that pattern.
Also, always log that failure even in the case of types defined in the
expression, as we've been recovering information for those types for a
while now.

rdar://96166383

Author: augusto2112

lldb/source/Plugins/TypeSystem/Swift/TypeSystemSwiftTypeRef.cpp

@@ -2520,18 +2520,15 @@ TypeSystemSwiftTypeRef::GetBitSize(opaque_compiler_type_t type,
             SwiftLanguageRuntime::Get(exe_scope->CalculateProcess())) {
       if (auto result = runtime->GetBitSize({this, type}, exe_scope))
         return result;
-      // If this is an expression context, perhaps the type was
-      // defined in the expression. In that case we don't have debug
-      // info for it, so defer to SwiftASTContext.
-      if (llvm::isa_and_nonnull<SwiftASTContextForExpressions>(
-              GetSwiftASTContext()))
-        return ReconstructType({this, type}).GetBitSize(exe_scope);
+      // Runtime failed, fallback to SwiftASTContext.
       LLDB_LOGF(GetLog(LLDBLog::Types),
                 "Couldn't compute size of type %s using SwiftLanguageRuntime.",
                 AsMangledName(type));
-      return {};
+      if (auto *swift_ast_context = GetSwiftASTContext())
+        return swift_ast_context->GetBitSize(ReconstructType(type), exe_scope);
     }
 
+
     // FIXME: Move this to the top. Currently this causes VALIDATE
     // errors on resilient types, and Foundation overlay types. These
     // are most likely bugs in the Swift compiler that need to be