Remove useless |kFormFieldTypes| constant.

Replace it with a loop using |kFormFieldTypeCount|.

Bug: pdfium:1428
Change-Id: Idf0a35748d3dab61122875322ee5d4768508c9a9
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/63735
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
diff --git a/fpdfsdk/cpdfsdk_interactiveform.cpp b/fpdfsdk/cpdfsdk_interactiveform.cpp
index 4b10400..54ec8b4 100644
--- a/fpdfsdk/cpdfsdk_interactiveform.cpp
+++ b/fpdfsdk/cpdfsdk_interactiveform.cpp
@@ -612,9 +612,9 @@
 }
 
 void CPDFSDK_InteractiveForm::SetAllHighlightColors(FX_COLORREF clr) {
-  for (auto type : kFormFieldTypes) {
-    m_HighlightColor[static_cast<size_t>(type)] = clr;
-    m_NeedsHighlight[static_cast<size_t>(type)] = true;
+  for (size_t i = 0; i < kFormFieldTypeCount; ++i) {
+    m_HighlightColor[i] = clr;
+    m_NeedsHighlight[i] = true;
   }
 }