- corrected delete in case we have more than one locals

- added a test

libsolidity/ExpressionCompiler.cpp

@@ -810,9 +810,9 @@ void ExpressionCompiler::LValue::setToZero(Expression const& _expression) const
 		if (stackDiff > 16)
 			BOOST_THROW_EXCEPTION(CompilerError() << errinfo_sourceLocation(_expression.getLocation())
 												  << errinfo_comment("Stack too deep."));
-		solAssert(stackDiff <= m_size, "");
+		solAssert(stackDiff >= m_size - 1, "");
 		for (unsigned i = 0; i < m_size; ++i)
-			*m_context << u256(0) << eth::swapInstruction(stackDiff + (m_size - i) )
+			*m_context << u256(0) << eth::swapInstruction(stackDiff + 1 - i)
 						<< eth::Instruction::POP;
 		break;
 	}

test/SolidityEndToEndTest.cpp

@@ -847,15 +847,17 @@ BOOST_AUTO_TEST_CASE(deleteLocals)
 {
 	char const* sourceCode = R"(
 		contract test {
-			function delLocal() returns (uint res){
+			function delLocal() returns (uint res1, uint res2){
 				uint v = 5;
 				uint w = 6;
+				uint x = 7;
 				delete v;
-				res = w;
+				res1 = w;
+				res2 = x;
 			}
 		})";
 	compileAndRun(sourceCode);
-	BOOST_CHECK(callContractFunction("delLocal()") == encodeArgs(6));
+	BOOST_CHECK(callContractFunction("delLocal()") == encodeArgs(6, 7));
 }
 
 BOOST_AUTO_TEST_CASE(constructor)