Abstract out fetching of break_address in debug mode

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 395ab77d8ace9116fb290d140da7a67d6ab468eb..0e3a98aeabb491ca05660b23d196bb9ceb9831a1 100644
--- a/src/mips64/assembler-mips64.h
+++ b/src/mips64/assembler-mips64.h
@@ -560,6 +560,9 @@ class Assembler : public AssemblerBase {
 
   static const int kPatchDebugBreakSlotReturnOffset = 6 * kInstrSize;
 
+  // Return the code target address of the patch debug break slot
+  inline static Address break_address_from_break_address(Address pc);
+
   // Number of instructions used for the JS return sequence. The constant is
   // used by the debugger to patch the JS return sequence.
   static const int kJSReturnSequenceInstructions = 7;