Rename Left() and Right() in {Byte,Wide}String{,View} classes

Rename to First() and Last().

Bug: pdfium:1406
Change-Id: I786313c4ea044c9e27e532d9d25ba6c26f9228f4
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/65613
Auto-Submit: Daniel Hosseinian <dhoss@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
diff --git a/fxjs/cjs_field.cpp b/fxjs/cjs_field.cpp
index ba0aa1e..b6aa9bb 100644
--- a/fxjs/cjs_field.cpp
+++ b/fxjs/cjs_field.cpp
@@ -148,7 +148,7 @@
     return;
   }
   WideString suffixal =
-      strFieldNameParsed.Right(reverse_it - strFieldNameParsed.rbegin());
+      strFieldNameParsed.Last(reverse_it - strFieldNameParsed.rbegin());
   iControlNo = FXSYS_wtoi(suffixal.c_str());
   if (iControlNo == 0) {
     suffixal.TrimRight(L' ');
@@ -159,7 +159,7 @@
     }
   }
   strFieldName =
-      strFieldNameParsed.Left(strFieldNameParsed.rend() - reverse_it - 1);
+      strFieldNameParsed.First(strFieldNameParsed.rend() - reverse_it - 1);
 }
 
 std::vector<CPDF_FormField*> GetFormFieldsForName(