M134: fix extraction of marked text

- ensure temp text buff appends marked text

Bug: 384770169, 395140023
Change-Id: I66bc81dc45017a8156b4a46529c9abf0f8630cec
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/127410
Reviewed-by: Thomas Sepez <tsepez@google.com>
Commit-Queue: Lei Zhang <thestig@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>
(cherry picked from commit c58db783d8dd299cdafd239472cf574f709fd1b5)
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/128710
Bot-Commit: rubber-stamper@appspot.gserviceaccount.com <rubber-stamper@appspot.gserviceaccount.com>

core/fpdftext/cpdf_textpage.cpp

diff --git a/core/fpdftext/cpdf_textpage.cpp b/core/fpdftext/cpdf_textpage.cpp
index f6d7e7e..697525e 100644
--- a/core/fpdftext/cpdf_textpage.cpp
+++ b/core/fpdftext/cpdf_textpage.cpp
@@ -984,6 +984,7 @@
 
     CFX_FloatRect char_box(rect);
     char_box.Translate(k * step, 0);
+    m_TempTextBuf.AppendChar(wChar);
     m_TempCharList.push_back(
         CharInfo(CharType::kPiece, font->CharCodeFromUnicode(wChar), wChar,
                  pTextObj->GetPos(), char_box, matrix, pTextObj));