Define a variable to distinguish system_icu from bundled_icu in Blink

LayoutTests/fast/encoding/char-encoding.html

Index: LayoutTests/fast/encoding/char-encoding.html
diff --git a/LayoutTests/fast/encoding/char-encoding.html b/LayoutTests/fast/encoding/char-encoding.html
index bb34346f4a9ed2a129562b3ba3dd6703f1e93564..3c131008be8d5326f91a3a150e3693ef39c509d1 100644
--- a/LayoutTests/fast/encoding/char-encoding.html
+++ b/LayoutTests/fast/encoding/char-encoding.html
@@ -34,11 +34,19 @@ testEncode('GBK', 'U+20AC', '%80');
 testEncode('gb2312', 'U+20AC', '%80');
 testEncode('GB_2312-80', 'U+20AC', '%80');
 testEncode('EUC-CN', 'U+20AC', '%80');
-//Misc symbols from TEC specific GBK translation
+//Align GBK with gb18030
+// See https://www.w3.org/Bugs/Public/show_bug.cgi?id=28740#c3
 testEncode('GBK', 'U+01F9', '%A8%BF');
 testEncode('GBK', 'U+1E3F', '%A8%BC');
-testEncode('GBK', 'U+22EF', '%A1%AD');
-testEncode('GBK', 'U+301C', '%A1%AB');
+testEncode('gb18030', 'U+01F9', '%A8%BF');
+testEncode('gb18030', 'U+1E3F', '%A8%BC');
+testEncode('GBK', 'U+2026', '%A1%AD');
+testEncode('GBK', 'U+FF5E', '%A1%AB');
+testEncode('gb18030', 'U+2026', '%A1%AD');
+testEncode('gb18030', 'U+FF5E', '%A1%AB');
+// GBK does not cover these two characters.
+testEncode('GBK', 'U+22EF', '%26%238943%3B');
+testEncode('GBK', 'U+301C', '%26%2312316%3B');
 
 // Replacement encodings - should encode as UTF-8
 testEncode("csiso2022kr", "U+00A0", "%C2%A0");