Start using C++17.

- Replace pdfium::size() with std::size().
- Update README.md.

Bug: pdfium:1766,pdfium:1780
Change-Id: Ie4dae21ec7da78cc32dab52f3580d6c94a9fa586
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/92790
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
diff --git a/fxjs/cjs_util_unittest.cpp b/fxjs/cjs_util_unittest.cpp
index 39b7318..832e0a5 100644
--- a/fxjs/cjs_util_unittest.cpp
+++ b/fxjs/cjs_util_unittest.cpp
@@ -4,8 +4,9 @@
 
 #include "fxjs/cjs_util.h"
 
+#include <iterator>
+
 #include "testing/gtest/include/gtest/gtest.h"
-#include "third_party/base/cxx17_backports.h"
 
 TEST(CJS_Util, ParseDataType) {
   struct ParseDataTypeCase {
@@ -105,7 +106,7 @@
       {L"%10s", CJS_Util::DataType::kString},
   };
 
-  for (size_t i = 0; i < pdfium::size(cases); i++) {
+  for (size_t i = 0; i < std::size(cases); i++) {
     WideString input(cases[i].input_string);
     EXPECT_EQ(cases[i].expected, CJS_Util::ParseDataType(&input))
         << cases[i].input_string;