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

src/mips64/assembler-mips64.h

Index: src/mips64/assembler-mips64.h
diff --git a/src/mips64/assembler-mips64.h b/src/mips64/assembler-mips64.h
index 056cc425f9235da8cd5aae03e8b64bd2530302f4..707fe88b748598e93326c0e6e500399d062f43f8 100644
--- a/src/mips64/assembler-mips64.h
+++ b/src/mips64/assembler-mips64.h
@@ -1091,9 +1091,6 @@ class Assembler : public AssemblerBase {
 
   // Debugging.
 
-  // Mark generator continuation.
-  void RecordGeneratorContinuation();
-
   // Mark address of a debug break slot.
   void RecordDebugBreakSlot(RelocInfo::Mode mode);