SyntaxHighlighter: Fix leaking

Change-Id: Icd9e6cb18facbcb28692db114b952e96a66e2836
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>
Reviewed-by: David Schulz <david.schulz@qt.io>

src/plugins/texteditor/syntaxhighlighter.cpp

@@ -9,8 +9,9 @@
 #include <utils/algorithm.h>
 #include <utils/qtcassert.h>
 
-#include <QTextDocument>
 #include <QPointer>
+#include <QTextDocument>
+#include <QThread>
 
 #include <cmath>
 
@@ -197,6 +198,9 @@ void SyntaxHighlighterPrivate::reformatBlocks(int from, int charsRemoved, int ch
     QList<SyntaxHighlighter::Result> vecRes;
 
     while (block.isValid() && (block.position() < endPosition || forceHighlightOfNextBlock)) {
+        if (QThread::currentThread()->isInterruptionRequested())
+            break;
+
         const int stateBeforeHighlight = block.userState();
 
         reformatBlock(block, from, charsRemoved, charsAdded);