Adding Stack Height Checker and modifying the number of POP instructions to appropriately provide the pointer address

test/libsolidity/semanticTests/functionTypes/stack_height_check_on_adding_gas_variable_to_function.sol

@@ -0,0 +1,25 @@
+contract C {
+    function g() external {}
+    function h() external payable {}
+    function test_function() external returns (bool){
+        assert (
+            this.g.address == this.g.address &&
+            this.g{gas: 42}.address == this.g.address &&
+            this.g{gas: 42}.selector == this.g.selector
+        );
+        assert (
+            this.h.address == this.h.address &&
+            this.h{gas: 42}.address == this.h.address &&
+            this.h{gas: 42}.selector == this.h.selector
+        );
+        assert (
+            this.h{gas: 42, value: 5}.address == this.h.address &&
+            this.h{gas: 42, value: 5}.selector == this.h.selector
+        );
+        return true;
+    }
+}
+// ====
+// compileViaYul: also
+// ----
+// test_function() -> true

test/libsolidity/syntaxTests/functionTypes/external_functions_with_variable_number_of_stack_slots.sol

@@ -0,0 +1,8 @@
+contract C {
+    function f (address) external returns (bool) {
+        this.f{gas: 42}.address;
+    }
+}
+// ----
+// Warning 6321: (56-60): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
+// Warning 2018: (17-102): Function state mutability can be restricted to view