A64: Tidy up a few TODOs.

src/a64/assembler-a64.h

Index: src/a64/assembler-a64.h
diff --git a/src/a64/assembler-a64.h b/src/a64/assembler-a64.h
index 3087e886f12c6cded30a652efa6083e1523e9735..999b01ad4ff05ad2a035510df3be75a37992115f 100644
--- a/src/a64/assembler-a64.h
+++ b/src/a64/assembler-a64.h
@@ -846,9 +846,6 @@ class Assembler : public AssemblerBase {
     return SizeOfCodeGeneratedSince(label) / kInstructionSize;
   }
 
-  // TODO(all): Initialize these constants related with code patching.
-  // TODO(all): Set to -1 to hopefully crash if mistakenly used.
-
   // Number of instructions generated for the return sequence in
   // FullCodeGenerator::EmitReturnSequence.
   static const int kJSRetSequenceInstructions = 7;