Add check for trivial string equality

core/fxcrt/fx_basic_wstring.cpp

Index: core/fxcrt/fx_basic_wstring.cpp
diff --git a/core/fxcrt/fx_basic_wstring.cpp b/core/fxcrt/fx_basic_wstring.cpp
index 8837c6bb3b3c854aef47b542b2efbe181a8b8e8e..88fc5889470129c012cee53fcd38b18d8d8c3005 100644
--- a/core/fxcrt/fx_basic_wstring.cpp
+++ b/core/fxcrt/fx_basic_wstring.cpp
@@ -180,6 +180,9 @@ bool CFX_WideString::operator==(const CFX_WideStringC& str) const {
 }
 
 bool CFX_WideString::operator==(const CFX_WideString& other) const {
+  if (m_pData == other.m_pData)
+    return true;
+
   if (IsEmpty())
     return other.IsEmpty();