Fix type inference issues for 'if' and 'when'.

Use 'expectedType' (when present) as an explicit type argument for a special construct call.
Unfortunately, this approach can't be used for elvis due to other elvis-related inference hacks.
Fixes KT-10807, KT-10811.
This also affects KT-6189: now we can infer proper type for 'if'.

If type inference for special call failed, and we found no type errors in sub-expressions,
report TYPE_INFERENCE_FAILED_ON_SPECIAL_CONSTRUCT error.
This (and the hack above) fixes KT-10809: code no longer compiles.

compiler/testData/diagnostics/tests/infos/SmartCasts.kt

@@ -181,8 +181,8 @@ fun returnFunctionLiteral(a: Any?): Function0<Int> {
     else return { -> 1 }
 }
 
-fun returnFunctionLiteralDoesntWork(a: Any?): Function0<Int> =
-        if (a is Int) <!TYPE_MISMATCH!>{ -> a }<!>
+fun returnFunctionLiteralExpressionBody(a: Any?): Function0<Int> =
+        if (a is Int) { -> <!DEBUG_INFO_SMARTCAST!>a<!> }
         else { -> 1 }