[stubs] Remove unused StoreGlobalViaContextStub.

src/arm64/interface-descriptors-arm64.cc

Index: src/arm64/interface-descriptors-arm64.cc
diff --git a/src/arm64/interface-descriptors-arm64.cc b/src/arm64/interface-descriptors-arm64.cc
index d7bc3de01a92915314d0ac1f4948ab3d5df20651..f4be0d52430c253b82c68685434931502c84964d 100644
--- a/src/arm64/interface-descriptors-arm64.cc
+++ b/src/arm64/interface-descriptors-arm64.cc
@@ -46,10 +46,6 @@ const Register StoreTransitionDescriptor::SlotRegister() { return x4; }
 const Register StoreTransitionDescriptor::VectorRegister() { return x3; }
 const Register StoreTransitionDescriptor::MapRegister() { return x5; }
 
-const Register StoreGlobalViaContextDescriptor::SlotRegister() { return x2; }
-const Register StoreGlobalViaContextDescriptor::ValueRegister() { return x0; }
-
-
 const Register StringCompareDescriptor::LeftRegister() { return x1; }
 const Register StringCompareDescriptor::RightRegister() { return x0; }