[turbofan] Fix undefined behavior in Int64Lowering.

This fixes undefined behavior introduced by extracting the const call
descriptor of a call node as non-const. Such an implicit cast between
constness is not safe and should be avoided.

R=ahaas@chromium.org
TEST=unittests/Int64LoweringTest.CallI64Parameter
BUG=v8:4924
LOG=n

Review URL: https://codereview.chromium.org/1900563002

Cr-Commit-Position: refs/heads/master@{#35569}

src/compiler/int64-lowering.cc

@@ -223,7 +223,9 @@ void Int64Lowering::LowerNode(Node* node) {
       break;
     }
     case IrOpcode::kCall: {
-      CallDescriptor* descriptor = OpParameter<CallDescriptor*>(node);
+      // TODO(turbofan): Make WASM code const-correct wrt. CallDescriptor.
+      CallDescriptor* descriptor =
+          const_cast<CallDescriptor*>(OpParameter<const CallDescriptor*>(node));
       if (DefaultLowering(node) ||
           (descriptor->ReturnCount() == 1 &&
            descriptor->GetReturnType(0) == MachineType::Int64())) {