Update an outdated comment in the CEntryStub on ARM.

src/arm/code-stubs-arm.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 3385 matching lines @@
       __ b(eq, &alignment_as_expected);
       // Don't use Check here, as it will call Runtime_Abort re-entering here.
       __ stop("Unexpected alignment");
       __ bind(&alignment_as_expected);
     }
   }
 #endif
 
   __ mov(r2, Operand(ExternalReference::isolate_address()));
 
-
-  // TODO(1242173): To let the GC traverse the return address of the exit
-  // frames, we need to know where the return address is. Right now,
-  // we store it on the stack to be able to find it again, but we never
-  // restore from it in case of changes, which makes it impossible to
-  // support moving the C entry code stub. This should be fixed, but currently
-  // this is OK because the CEntryStub gets generated so early in the V8 boot
-  // sequence that it is not moving ever.
-
+  // To let the GC traverse the return address of the exit frames, we need to
+  // know where the return address is. The CEntryStub is unmovable, so
+  // we can store the address on the stack to be able to find it again and
+  // we never have to restore it, because it will not change.
   // Compute the return address in lr to return to after the jump below. Pc is
   // already at '+ 8' from the current instruction but return is after three
   // instructions so add another 4 to pc to get the return address.
   masm->add(lr, pc, Operand(4));
   __ str(lr, MemOperand(sp, 0));
   masm->Jump(r5);
 
   if (always_allocate) {
     // It's okay to clobber r2 and r3 here. Don't mess with r0 and r1
     // though (contain the result).
@@ skipping 2977 matching lines @@
   __ mov(result, Operand(0));
   __ Ret();
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM