Scheme of content utils should be compared in an ASCII case-insensitive manner

Source/modules/navigatorcontentutils/NavigatorContentUtils.cpp

Index: Source/modules/navigatorcontentutils/NavigatorContentUtils.cpp
diff --git a/Source/modules/navigatorcontentutils/NavigatorContentUtils.cpp b/Source/modules/navigatorcontentutils/NavigatorContentUtils.cpp
index 42cb15491abe7a347e9791b167daa21ecb74de20..2c42b51c1d3e04ff9f7cddf9a9bd8e9f71ada56a 100644
--- a/Source/modules/navigatorcontentutils/NavigatorContentUtils.cpp
+++ b/Source/modules/navigatorcontentutils/NavigatorContentUtils.cpp
@@ -34,6 +34,7 @@
 #include "core/frame/Navigator.h"
 #include "core/page/Page.h"
 #include "wtf/HashSet.h"
+#include "wtf/text/StringBuilder.h"
 
 namespace WebCore {
 
@@ -97,7 +98,18 @@ static bool isProtocolWhitelisted(const String& scheme)
 {
     if (!protocolWhitelist)
         initProtocolHandlerWhitelist();
-    return protocolWhitelist->contains(scheme);
+
+    StringBuilder builder;
+    unsigned length = scheme.length();
+    for (unsigned i = 0; i < length; ++i) {
+        UChar character = scheme[i];
+        if (isASCIIUpper(character))
+            builder.append(toASCIILower(character));
+        else
+            builder.append(character);

[haraken, 2014/06/07 02:19:23]

Do we need this branch? I guess builder.append(toASCIILower(character)) works as
expected for lower characters as well.

[gyuyoung-inactive, 2014/06/07 06:28:51]

Doesn't this operation always call toASCIILower() function even when character
is ASCII lowercase ? Of course, it looks it is trivial overhead.

[haraken, 2014/06/07 06:36:49]

I mean, you can remove line 106 - 109 and just use
builder.append(toASCIILower(character)).

The difference is just whether you check isASCIIUpper(character) in the caller
side or the callee side.

[gyuyoung-inactive, 2014/06/07 06:51:01]

Ah...yes. we can avoid to call isASCIIUpper() when using your suggestion.
Calling overhead looks same. 

+    }
+
+    return protocolWhitelist->contains(builder.toString());
 }
 
 static bool verifyProtocolHandlerScheme(const String& scheme, const String& method, ExceptionState& exceptionState)