Removed unused helper function

XFA_FM_KeywordToString is no longer used, and there are no plans to
use it in the future, so should be removed.

Bug:
Change-Id: I44652a40f6396b25262f840c42036fb00a14aca1
Reviewed-on: https://pdfium-review.googlesource.com/9210
Commit-Queue: Ryan Harrison <rharrison@chromium.org>
Reviewed-by: dsinclair <dsinclair@chromium.org>
diff --git a/xfa/fxfa/fm2js/cxfa_fmlexer.cpp b/xfa/fxfa/fm2js/cxfa_fmlexer.cpp
index c8a064f..dc86c23 100644
--- a/xfa/fxfa/fm2js/cxfa_fmlexer.cpp
+++ b/xfa/fxfa/fm2js/cxfa_fmlexer.cpp
@@ -98,25 +98,19 @@
 XFA_FM_TOKEN TokenizeIdentifier(const CFX_WideStringC& str) {
   uint32_t key = FX_HashCode_GetW(str, true);
 
+  const XFA_FMKeyword* end = std::begin(keyWords) + KEYWORD_END + 1;
   const XFA_FMKeyword* result =
-      std::lower_bound(std::begin(keyWords) + KEYWORD_START, std::end(keyWords),
-                       key, [](const XFA_FMKeyword& iter, const uint32_t& val) {
+      std::lower_bound(std::begin(keyWords) + KEYWORD_START, end, key,
+                       [](const XFA_FMKeyword& iter, const uint32_t& val) {
                          return iter.m_hash < val;
                        });
-  if (result != std::end(keyWords) && result->m_hash == key) {
+  if (result != end && result->m_hash == key)
     return result->m_type;
-  }
   return TOKidentifier;
 }
 
 }  // namespace
 
-const wchar_t* XFA_FM_KeywordToString(XFA_FM_TOKEN op) {
-  if (op < KEYWORD_START || op > KEYWORD_END)
-    return L"";
-  return keyWords[op].m_keyword;
-}
-
 CXFA_FMToken::CXFA_FMToken() : m_type(TOKreserver), m_line_num(1) {}
 
 CXFA_FMToken::CXFA_FMToken(uint32_t line_num)
diff --git a/xfa/fxfa/fm2js/cxfa_fmlexer.h b/xfa/fxfa/fm2js/cxfa_fmlexer.h
index c944266..b3f13da 100644
--- a/xfa/fxfa/fm2js/cxfa_fmlexer.h
+++ b/xfa/fxfa/fm2js/cxfa_fmlexer.h
@@ -89,8 +89,6 @@
   const wchar_t* m_keyword;
 };
 
-const wchar_t* XFA_FM_KeywordToString(XFA_FM_TOKEN op);
-
 class CXFA_FMToken {
  public:
   CXFA_FMToken();