[turbofan] Initial support for Switch.

src/disassembler.cc

Index: src/disassembler.cc
diff --git a/src/disassembler.cc b/src/disassembler.cc
index a411d7c25ed7dc186e49c13d14eb6a8c8f99748b..e0316441afef180e222ce30b908adbc425787caf 100644
--- a/src/disassembler.cc
+++ b/src/disassembler.cc
@@ -115,7 +115,7 @@ static int DecodeIt(Isolate* isolate, std::ostream* os,
                  "%08" V8PRIxPTR "      jump table entry %4" V8PRIdPTR,
                  reinterpret_cast<intptr_t>(ptr),
                  ptr - begin);
-        pc += 4;
+        pc += sizeof(ptr);
       } else {
         decode_buffer[0] = '\0';
         pc += d.InstructionDecode(decode_buffer, pc);