Clear CPWL_EditImpl_Refresh::m_NewLineRects after move.

Avoid the possibility of "valid but unspecified" state gotcha
with std::move() of std::vector<>.

Change-Id: I41b8b6ba0812d336a6c1153961a88bcebe2b125e
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/52512
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Tom Sepez <tsepez@chromium.org>

fpdfsdk/pwl/cpwl_edit_impl.cpp

diff --git a/fpdfsdk/pwl/cpwl_edit_impl.cpp b/fpdfsdk/pwl/cpwl_edit_impl.cpp
index efdd49e..c4e3ff4 100644
--- a/fpdfsdk/pwl/cpwl_edit_impl.cpp
+++ b/fpdfsdk/pwl/cpwl_edit_impl.cpp
@@ -165,8 +165,9 @@
 CPWL_EditImpl_Refresh::~CPWL_EditImpl_Refresh() {}
 
 void CPWL_EditImpl_Refresh::BeginRefresh() {
-  m_RefreshRects.clear();
   m_OldLineRects = std::move(m_NewLineRects);
+  m_NewLineRects.clear();
+  m_RefreshRects.clear();
 }
 
 void CPWL_EditImpl_Refresh::Push(const CPVT_WordRange& linerange,