Add constants for PDF 1.7 spec, table 8.15.

BUG=pdfium:1049

Change-Id: I09fb1c34b8f08ce5c5b5f86e7fe64dfd11ed770d
Reviewed-on: https://pdfium-review.googlesource.com/c/49571
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
diff --git a/fpdfsdk/BUILD.gn b/fpdfsdk/BUILD.gn
index 87eac73..e66b9e4 100644
--- a/fpdfsdk/BUILD.gn
+++ b/fpdfsdk/BUILD.gn
@@ -134,6 +134,7 @@
   ]
   deps = [
     ":fpdfsdk",
+    "../constants",
     "../core/fpdfapi/font",
     "../core/fpdfapi/page",
     "../core/fpdfapi/parser",