Clarify result returned by remainder intrinsics.

runtime/vm/intrinsifier_ia32.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 //
 // The intrinsic code below is executed before a method has built its frame.
 // The return address is on the stack and the arguments below it.
 // Registers EDX (arguments descriptor) and ECX (function) must be preserved.
 // Each intrinsification method returns true if the corresponding
 // Dart method was intrinsified.
 
@@ skipping 360 matching lines @@
 
 
 // Optimizations:
 // - result is 0 if:
 //   - left is 0
 //   - left equals right
 // - result is left if
 //   - left > 0 && left < right
 // EAX: Tagged left (dividend).
 // EBX: Tagged right (divisor).
-// EDX: Untagged result (remainder).
+// Returns:
+//   EDX: Untagged fallthrough result (remainder to be adjusted), or
+//   EAX: Tagged return result (remainder).
 static void EmitRemainderOperation(Assembler* assembler) {
   Label return_zero, modulo;
   // Check for quick zero results.
   __ cmpl(EAX, Immediate(0));
   __ j(EQUAL, &return_zero, Assembler::kNearJump);
   __ cmpl(EAX, EBX);
   __ j(EQUAL, &return_zero, Assembler::kNearJump);
 
   // Check if result equals left.
   __ cmpl(EAX, Immediate(0));
@@ skipping 1636 matching lines @@
                         Isolate::current_tag_offset());
   // Set return value to Isolate::current_tag_.
   __ movl(EAX, current_tag_addr);
   __ ret();
 }
 
 #undef __
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_IA32