Restrict size for dynamic memory array creation.

test/libsolidity/semanticTests/array/create_memory_array_too_large.sol

@@ -0,0 +1,24 @@
+contract C {
+    function f() public returns (uint256) {
+        uint256 l = 2**256 / 32;
+        // This used to work without causing an error.
+        uint256[] memory x = new uint256[](l);
+        uint256[] memory y = new uint256[](1);
+        x[1] = 42;
+        // This used to overwrite the value written above.
+        y[0] = 23;
+        return x[1];
+    }
+    function g() public returns (uint256) {
+        uint256 l = 2**256 / 2 + 1;
+        // This used to work without causing an error.
+        uint16[] memory x = new uint16[](l);
+        uint16[] memory y = new uint16[](1);
+        x[2] = 42;
+        // This used to overwrite the value written above.
+        y[0] = 23;
+        return x[2];
+    }}
+// ----
+// f() -> FAILURE
+// g() -> FAILURE