Remove some leftovers of full-codegen's generators implementation.

src/x87/assembler-x87.h

Index: src/x87/assembler-x87.h
diff --git a/src/x87/assembler-x87.h b/src/x87/assembler-x87.h
index 160145b5ad6b35f0fa0df0445235a7aa3b9fb80a..22339e749510a52b8bda181429955fc7e3b8ca1c 100644
--- a/src/x87/assembler-x87.h
+++ b/src/x87/assembler-x87.h
@@ -957,9 +957,6 @@ class Assembler : public AssemblerBase {
     return pc_offset() - label->pos();
   }
 
-  // Mark generator continuation.
-  void RecordGeneratorContinuation();
-
   // Mark address of a debug break slot.
   void RecordDebugBreakSlot(RelocInfo::Mode mode);