Fraction class prototype and test (not to be committed).

runtime/vm/intrinsifier_arm64.cc

Index: runtime/vm/intrinsifier_arm64.cc
diff --git a/runtime/vm/intrinsifier_arm64.cc b/runtime/vm/intrinsifier_arm64.cc
index f9cade23e23862b21a0e420bfca5e49edc80bee3..e7466ad1e673172f644c1ba4ec2184fbd0dd9f3f 100644
--- a/runtime/vm/intrinsifier_arm64.cc
+++ b/runtime/vm/intrinsifier_arm64.cc
@@ -608,11 +608,14 @@ void Intrinsifier::Integer_equalToInteger(Assembler* assembler) {
   __ tsti(R1, Immediate(kSmiTagMask));  // Check receiver.
   __ b(&receiver_not_smi, NE);
 
-  // Left (receiver) is Smi, return false if right is not Double.
+  // Left (receiver) is Smi, return false if right is not Double or Fraction.
   // Note that an instance of Mint or Bigint never contains a value that can be
   // represented by Smi.
 
-  __ CompareClassId(R0, kDoubleCid);
+  __ LoadClassId(TMP, R0);
+  __ CompareImmediate(TMP, kDoubleCid);
+  __ b(&fall_through, EQ);
+  __ CompareImmediate(TMP, kFractionCid);
   __ b(&fall_through, EQ);
   __ LoadObject(R0, Bool::False());  // Smi == Mint -> false.
   __ ret();