API: Generate head items in the context of the given title

$context->getOutput() returns an OutputPage tied to the main
RequestContext at the root of the chain, not to the modified context
we're actually using.

Bug: T139565
Change-Id: Ie086d7f2ad3f7b5f50e3a2f83b1680e760b85e5e

diff --git a/includes/api/ApiParse.php b/includes/api/ApiParse.php
index f96acf3..3e66cad 100644 (file)
--- a/includes/api/ApiParse.php
+++ b/includes/api/ApiParse.php
@@ -346,22 +346,27 @@ class ApiParse extends ApiBase {
                }
 
                if ( isset( $prop['headitems'] ) || isset( $prop['headhtml'] ) ) {
-                       $context = $this->getContext();
+                       $context = new DerivativeContext( $this->getContext() );
                        $context->setTitle( $titleObj );
-                       $context->getOutput()->addParserOutputMetadata( $p_result );
+                       $context->setWikiPage( $pageObj );
+
+                       // We need an OutputPage tied to $context, not to the
+                       // RequestContext at the root of the stack.
+                       $output = new OutputPage( $context );
+                       $output->addParserOutputMetadata( $p_result );
 
                        if ( isset( $prop['headitems'] ) ) {
                                $headItems = $this->formatHeadItems( $p_result->getHeadItems() );
 
-                               $css = $this->formatCss( $context->getOutput()->buildCssLinksArray() );
+                               $css = $this->formatCss( $output->buildCssLinksArray() );
 
-                               $scripts = [ $context->getOutput()->getHeadScripts() ];
+                               $scripts = [ $output->getHeadScripts() ];
 
                                $result_array['headitems'] = array_merge( $headItems, $css, $scripts );
                        }
 
                        if ( isset( $prop['headhtml'] ) ) {
-                               $result_array['headhtml'] = $context->getOutput()->headElement( $context->getSkin() );
+                               $result_array['headhtml'] = $output->headElement( $context->getSkin() );
                                $result_array[ApiResult::META_BC_SUBELEMENTS][] = 'headhtml';
                        }
                }