Implement .creationCode for Sol->Yul.

test/libsolidity/semanticTests/constructor/callvalue_check.sol

@@ -29,6 +29,7 @@ contract C {
 }
 // ====
 // EVMVersion: >homestead
+// compileViaYul: also
 // ----
 // f(uint256), 2000 ether: 0 -> true
 // f(uint256), 2000 ether: 100 -> false

test/libsolidity/semanticTests/various/code_access_create.sol

@@ -22,5 +22,7 @@ contract C {
     }
 }
 
+// ====
+// compileViaYul: also
 // ----
 // test() -> 7

test/libsolidity/semanticTests/various/code_access_runtime.sol

@@ -0,0 +1,27 @@
+contract D {
+    uint256 x;
+
+    constructor() public {
+        x = 7;
+    }
+
+    function f() public view returns (uint256) {
+        return x;
+    }
+}
+
+
+contract C {
+    function test() public returns (uint256) {
+	D d = new D();
+	bytes32 hash;
+	assembly { hash := extcodehash(d) }
+	assert(hash == keccak256(type(D).runtimeCode));
+	return 42;
+    }
+}
+
+// ====
+// EVMVersion: >=constantinople
+// ----
+// test() -> 42