Escape JavaScript code in wxJSScriptWrapper constructor

We can prepare the escaped code directly here, instead of waiting for
GetWrappedCode() call, this is more clear and safer as it avoids
escaping the code twice accidentally if GetWrappedCode() ends up being
called twice somehow.

include/wx/private/jsscriptwrapper.h

@@ -20,6 +20,7 @@ class wxJSScriptWrapper
 {
 public:
     wxJSScriptWrapper(const wxString& js, int* runScriptCount) : m_jsscript(js)
+        : m_escapedCode(js)
     {
         // We assign the return value of JavaScript snippet we execute to the
         // variable with this name in order to be able to access it later if
@@ -29,19 +30,19 @@ public:
         // RunScript() (which creates a new wxJSScriptWrapper every time) to
         // avoid any possible conflict between different calls.
         m_outputVarName = wxString::Format("__wxOut%i", (*runScriptCount)++);
+
+        // Adds one escape level if there is a single quote, double quotes or
+        // escape characters
+        wxRegEx escapeDoubleQuotes("(\\\\*)(['\"\n\r\v\t\b\f])");
+        escapeDoubleQuotes.Replace(&m_escapedCode,"\\1\\1\\\\\\2");
     }
 
     // This method is used to add a double quote level into a JavaScript code
     // in order to get it working when eval is called programmatically.
     const wxString GetWrappedCode()
     {
-        // Adds one escape level if there is a single quote, double quotes or
-        // escape characters
-        wxRegEx escapeDoubleQuotes("(\\\\*)(['\"\n\r\v\t\b\f])");
-        escapeDoubleQuotes.Replace(&m_jsscript,"\\1\\1\\\\\\2");
-
         return wxString::Format("try { var %s = eval(\"%s\"); true; } \
-            catch (e) { e.name + \": \" + e.message; }", m_outputVarName, m_jsscript);;
+            catch (e) { e.name + \": \" + e.message; }", m_outputVarName, m_escapedCode);
     }
 
     const wxString GetOutputCode()
@@ -141,7 +142,7 @@ public:
     }
 
 private:
-    wxString m_jsscript;
+    wxString m_escapedCode;
     wxString m_outputVarName;
 
     wxDECLARE_NO_COPY_CLASS(wxJSScriptWrapper);