Special printing for type feedback vectors.

tools/gdbinit

Index: tools/gdbinit
diff --git a/tools/gdbinit b/tools/gdbinit
index 72030e269a086d77162ee30a0150a48946cbebc7..5e6af9d6a89ed00d9b977582a3d44b8743e1fe10 100644
--- a/tools/gdbinit
+++ b/tools/gdbinit
@@ -20,6 +20,15 @@ Print a v8 Code object from an internal code address
 Usage: jco pc
 end
 
+# Print TypeFeedbackVector
+define jfv
+print ((v8::internal::TypeFeedbackVector*)($arg0))->Print()
+end
+document jfv
+Print a v8 TypeFeedbackVector object
+Usage: jtv tagged_ptr
+end
+
 # Print DescriptorArray.
 define jda
 print ((v8::internal::DescriptorArray*)($arg0))->Print()