Unicode Variation Selectors support in collectCandidateRuns

Source/platform/fonts/Character.h

Index: Source/platform/fonts/Character.h
diff --git a/Source/platform/fonts/Character.h b/Source/platform/fonts/Character.h
index b2a76fe5ceb69ebd3e487344597e32da0f04c486..eeffbc68ee348496f5b436a679f83769dea155a9 100644
--- a/Source/platform/fonts/Character.h
+++ b/Source/platform/fonts/Character.h
@@ -51,6 +51,14 @@ public:
         return character >= lowerBound && character <= upperBound;
     }
 
+    static inline bool isUnicodeVariationSelector(UChar32 character)
+    {
+        // http://www.unicode.org/Public/UCD/latest/ucd/StandardizedVariants.html
+        return isInRange(character, 0x180B, 0x180D) // MONGOLIAN FREE VARIATION SELECTOR ONE to THREE
+            || isInRange(character, 0xFE00, 0xFE0F) // VARIATION SELECTOR-1 to 16
+            || isInRange(character, 0xE0100, 0xE01EF); // VARIATION SELECTOR-17 to 256
+    }
+
     static bool isCJKIdeograph(UChar32);
     static bool isCJKIdeographOrSymbol(UChar32);