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/when/kt10809.kt

@@ -0,0 +1,50 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -DEBUG_INFO_SMARTCAST
+
+interface Data
+interface Item
+class FlagData(val value: Boolean) : Data
+class ListData<T : Item>(val list: List<T>) : Data
+
+fun <T> listOf(vararg items: T): List<T> = null!!
+
+fun test1(o: Any) = <!TYPE_INFERENCE_FAILED_ON_SPECIAL_CONSTRUCT!>when<!> (o) {
+    is List<*> ->
+        ListData(listOf())
+    is Int -> when {
+        o < 0 ->
+            FlagData(true)
+        else ->
+            null
+    }
+    else ->
+        null
+}
+
+fun test1x(o: Any): Data? = when (o) {
+    is List<*> ->
+        ListData(listOf())
+    is Int -> when {
+        o < 0 ->
+            FlagData(true)
+        else ->
+            null
+    }
+    else ->
+        null
+}
+
+fun test2() =
+        <!TYPE_INFERENCE_FAILED_ON_SPECIAL_CONSTRUCT!>if<!> (true)
+            ListData(listOf())
+        else
+            FlagData(true)
+
+fun test2x(): Data =
+        if (true) ListData(listOf()) else FlagData(true)
+
+fun test2y(): Any =
+        if (true) ListData(listOf()) else FlagData(true)
+
+fun test2z(): Any =
+        run { if (true) ListData(listOf()) else FlagData(true) }
+