XFA: merge patch from CL 733693003, getting rid of more casts

Getting rid of more (FX_LPCWSTR) casts and fixing two bugs revealed by this.

Since casts to FX_LPCWSTR have been shown to hide bugs I tried removing
more of them, targeting those places where a cast was used to force a
conversion from CFX_WideString to FX_LPCWSTR, replacing these casts with
calls to the newly added .c_str() function. This revealed two places
where the cast was hiding a bug -- where ->c_str() was required instead!

This removes ~33 FX_LPCWSTR casts and there are ~31 left, many of which
will go away in some future change.

Also includes this change:

Removing unnecessary casts from wchar_t* to wchar_t*, by various names.

Original patch from Bruce Dawson(brucedawson@chromium.org)

TBR=bo_xu@foxitsoftware.com, tsepez@chromium.org

Review URL: https://codereview.chromium.org/811593007
diff --git a/fpdfsdk/src/javascript/PublicMethods.cpp b/fpdfsdk/src/javascript/PublicMethods.cpp
index 4c51c9a..82bffe6 100644
--- a/fpdfsdk/src/javascript/PublicMethods.cpp
+++ b/fpdfsdk/src/javascript/PublicMethods.cpp
@@ -1554,7 +1554,7 @@
 	if (JS_PortIsNan(dDate))
 	{
 		CFX_WideString swMsg;
-		swMsg.Format(JSGetStringFromID(pContext, IDS_STRING_JSPARSEDATE), (FX_LPCWSTR)sFormat);
+		swMsg.Format(JSGetStringFromID(pContext, IDS_STRING_JSPARSEDATE), sFormat.c_str());
 		Alert(pContext, swMsg);
 		return FALSE;
 	}
@@ -1652,7 +1652,7 @@
 		if (bWrongFormat || JS_PortIsNan(dRet))
 		{
 			CFX_WideString swMsg;
-			swMsg.Format(JSGetStringFromID(pContext, IDS_STRING_JSPARSEDATE), (FX_LPCWSTR)sFormat);
+			swMsg.Format(JSGetStringFromID(pContext, IDS_STRING_JSPARSEDATE), sFormat.c_str());
 			Alert(pContext, swMsg);
 			pEvent->Rc() = FALSE;
 			return TRUE;
@@ -2059,7 +2059,7 @@
 	if (JS_PortIsNan(dDate))
 	{
 		CFX_WideString swMsg;
-		swMsg.Format(JSGetStringFromID(pContext, IDS_STRING_JSPARSEDATE), (FX_LPCWSTR)sFormat);
+		swMsg.Format(JSGetStringFromID(pContext, IDS_STRING_JSPARSEDATE), sFormat.c_str());
 		Alert((CJS_Context *)cc, swMsg);
 		return FALSE;
 	}
@@ -2304,7 +2304,7 @@
 		{
 			if (sPart.GetLength() > 0)
 			{
-				nums.SetElement(nIndex,CJS_Value(isolate,(FX_LPCWSTR)sPart));
+				nums.SetElement(nIndex,CJS_Value(isolate,sPart.c_str()));
 				sPart = L"";
 				nIndex ++;
 			}
@@ -2313,7 +2313,7 @@
 
 	if (sPart.GetLength() > 0)
 	{
-		nums.SetElement(nIndex,CJS_Value(isolate,(FX_LPCWSTR)sPart));	
+		nums.SetElement(nIndex,CJS_Value(isolate,sPart.c_str()));	
 	}
 
 	if (nums.GetLength() > 0)