Correctly indent the RHS of 'is' and 'as' expressions.

test/splitting/mixed.stmt

 40 columns                              |
 >>> keeps map on one line if possible
 sendPort.send({'type': 'error', 'error': 'oops'});
 <<<
 sendPort.send(
     {'type': 'error', 'error': 'oops'});
 >>> prefers to wrap before "."
 new Future.sync(() => callback('msg')).then(
     (result) => replyTo.send()).catchError((error) {});
 <<<
@@ skipping 192 matching lines @@
 veryLongFunction() => extremelyLongArgument + argument;
 <<<
 veryLongFunction() =>
     extremelyLongArgument + argument;
 >>> no extra indent before binary operators in => body
 veryLongFunction() => longArgument + longArgument + longArgument;
 <<<
 veryLongFunction() =>
     longArgument +
     longArgument +
-    longArgument;
+    longArgument;
+>>> initialize with as expression
+var longVariableName = identifierSoLongItWraps as SomeClassName;
+<<<
+var longVariableName =
+    identifierSoLongItWraps
+        as SomeClassName;
+>>> initialize with is expression
+var longVariableName = identifierSoLongItWraps is SomeClassName;
+<<<
+var longVariableName =
+    identifierSoLongItWraps
+        is SomeClassName;