[lldb] Resolve imports before manipulating AST

Imports need to be resolved before the SwiftASTManipulator
is run, as it can query interface types.

Author: hamishknight

lldb/source/Plugins/ExpressionParser/Swift/SwiftExpressionParser.cpp

@@ -1280,6 +1280,13 @@ static llvm::Expected<ParsedExpression> ParseAndImport(
   //        inserting them in.
   swift_ast_context->AddDebuggerClient(external_lookup);
 
+  if (swift_ast_context->HasErrors())
+    return make_error<SwiftASTContextError>();
+
+  // Resolve the file's imports, including the implicit ones returned from
+  // GetImplicitImports.
+  swift::performImportResolution(*source_file);
+
   if (swift_ast_context->HasErrors())
     return make_error<SwiftASTContextError>();
 
@@ -1331,11 +1338,6 @@ static llvm::Expected<ParsedExpression> ParseAndImport(
     stack_frame_sp.reset();
   }
 
-  swift::performImportResolution(*source_file);
-
-  if (swift_ast_context->HasErrors())
-    return make_error<SwiftASTContextError>();
-
   // Cache the source file's imports such that they're accessible to future
   // expression evaluations.
   {