[Sol->Yul] Implementing resizing of dynamic byte arrays

Co-authored-by: chriseth <chris@ethereum.org>

test/libsolidity/semanticTests/array/byte_array_storage_layout.sol

@@ -32,6 +32,7 @@ contract c {
             data.push(bytes1(i));
         }
         data.pop();
+        data.pop();
         assembly {
             r := sload(data.slot)
         }
@@ -42,4 +43,4 @@ contract c {
 // ----
 // test_short() -> 1780731860627700044960722568376587075150542249149356309979516913770823710
 // test_long() -> 67
-// test_pop() -> 1780731860627700044960722568376592200742329637303199754547598369979440702
+// test_pop() -> 1780731860627700044960722568376592200742329637303199754547598369979433020

test/libsolidity/semanticTests/array/delete_bytes_array.sol

@@ -0,0 +1,37 @@
+contract C {
+    bytes data;
+
+    function f() public returns (uint ret) {
+        data.push("a");
+        data.push("b");
+        delete data;
+        assembly {
+            ret := sload(data.slot)
+        }
+    }
+
+    function g() public returns (uint ret) {
+        assembly {
+            sstore(data.slot, 67)
+        }
+        data.push("a");
+        data.push("b");
+        assert(data.length == 35);
+        delete data;
+        assert(data.length == 0);
+
+        uint size = 999;
+        assembly {
+            size := sload(data.slot)
+            mstore(0, data.slot)
+            ret := sload(keccak256(0, 32))
+        }
+        assert(size == 0);
+    }
+}
+
+// ====
+// compileViaYul: also
+// ----
+// f() -> 0
+// g() -> 0