QV4: Fix formatting options for the search component of UrlObject

This fix changes the way the search component of UrlObjects is formatted
by passing the correct options to QUrl::query. Namely, the
EncodeDelimiters flag is no longer set. This now allows for correct
encoding of backslashes in search strings.

Amends 6cca731f3e.

Pick-to: 6.5
Task-number: QTBUG-111014
Change-Id: Iee544dfc7ad6ba374601c8ec4690d11bf07c9b6a
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>

src/qml/jsruntime/qv4urlobject.cpp

@@ -248,7 +248,10 @@ QString UrlObject::search() const
     if (auto url = QUrl(href()); !url.hasQuery() || url.query().isEmpty())
         return QLatin1String("");
 
-    return QLatin1Char('?') + url.query(QUrl::ComponentFormattingOptions(QUrl::ComponentFormattingOption::FullyEncoded));
+    constexpr auto options = QUrl::ComponentFormattingOption::EncodeSpaces
+            | QUrl::ComponentFormattingOption::EncodeUnicode
+            | QUrl::ComponentFormattingOption::EncodeReserved;
+    return u'?' + url.query(options);
 }
 
 QUrl UrlObject::toQUrl() const

tests/auto/qml/qv4urlobject/tst_qv4urlobject.cpp

@@ -116,6 +116,14 @@ void tst_urlobject::urlObject_search_data()
             << "var url = new URL(\"http://google.com/search/?a=㉽\");"
                "url.search"
             << "?a=%E3%89%BD";
+    QTest::newRow("backslash")
+            // The JS string in the C++ source ends in 4 backslashes.
+            // The C++ compiler turns that into 2 backslashes.
+            // QV4 receives source code containing a string literal ending in two backslashes.
+            // The resulting JS string ends in a single backslash.
+            << "var url = new URL('http://google.com/search/?q=\\\\');"
+               "url.search"
+            << "?q=\\";
 }
 
 void tst_urlobject::urlObject_href()