Remove CFX_{Byte,Wide}String::Equal in favor of "==".

Makes the code slightly cleaner.

Review URL: https://codereview.chromium.org/1846083002
diff --git a/fpdfsdk/fpdfdoc.cpp b/fpdfsdk/fpdfdoc.cpp
index 1b2daae..c9030e5 100644
--- a/fpdfsdk/fpdfdoc.cpp
+++ b/fpdfsdk/fpdfdoc.cpp
@@ -291,7 +291,7 @@
         ToDictionary(static_cast<CPDF_Object*>(pAnnots->GetDirectObjectAt(i)));
     if (!pDict)
       continue;
-    if (pDict->GetStringBy("Subtype").Equal("Link")) {
+    if (pDict->GetStringBy("Subtype") == "Link") {
       *startPos = i + 1;
       *linkAnnot = (FPDF_LINK)pDict;
       return TRUE;