Add SB Curated (copied from the smartbugs repository).

dataset/denial_of_service/dos_address.sol

@@ -0,0 +1,36 @@
+/*
+ * @source: https://github.com/SmartContractSecurity/SWC-registry/blob/master/test_cases/dos_gas_limit/dos_address.sol
+ * @author: -
+ * @vulnerable_at_lines: 16,17,18
+ */
+
+pragma solidity ^0.4.25;
+
+contract DosGas {
+
+    address[] creditorAddresses;
+    bool win = false;
+
+    function emptyCreditors() public {
+        // <yes> <report> DENIAL_OF_SERVICE
+        if(creditorAddresses.length>1500) {
+            creditorAddresses = new address[](0);
+            win = true;
+        }
+    }
+
+    function addCreditors() public returns (bool) {
+        for(uint i=0;i<350;i++) {
+          creditorAddresses.push(msg.sender);
+        }
+        return true;
+    }
+
+    function iWin() public view returns (bool) {
+        return win;
+    }
+
+    function numberCreditors() public view returns (uint) {
+        return creditorAddresses.length;
+    }
+}