[flow] make EMethodUnbinding defered_in_speculation

Summary:
The difference in behavior can be seen in the example:
```
interface MethLike { m(): number }
interface PropLike { m: () => string; }

declare const obj: MethLike & PropLike;
```
Before this change, calling `obj.m` and calling `obj.m()` had a weird inconsistency:
```
obj.m as () => string; // no error
obj.m() as number; // no error
```
as Flow would pick `.m` from different definitions each time.

Accessing `obj.m` would cause a [method-unbinding] on `MethLike`, so in the first line we would pick `.m` off of `PropLike`. In the second case, we wouldn't get a [method-unbinding] error and so we would eventually get a number.

With this change the following
```
obj.m as () => number;
obj.m() as number;
```
has no type incompatibility, but we still raise the method-unbinding error in the first case.

Changelog: [errors] method-unbinding errors will not affect choice over intersection members. (e.g. [try-Flow](https://flow.org/try/#1N4Igxg9gdgZglgcxALlAIwIZoKYBsD6uEEAztvhgE6UYCe+JADpdhgCYowa5kA0I2KAFcAtiRQAXSkOz9sADwxgJ+NPTbYuQ3BMnTZA+Y2yU4IwRO4A6SFBIrGVDGM7c+h46fNRLuKxJIGWh8MeT0ZfhYlCStpHzNsFBAMIQkIEQwJODAQfiEyfBE4eWw2fDgofDBMsAALfAA3KjgsXGxxZC4eAw0G-GhcWn9aY3wWZldu-g1mbGqJUoBaCRHEzrcDEgBrbAk62kXhXFxJ923d-cPRHEpTgyEoMDaqZdW7vKgoOfaSKgOKpqmDA+d4gB5fMA-P6LCCMLLQbiLOoYCqgh6-GDYRYIXYLSgkRZkCR4jpddwPfJLZjpOBkO4AX34kA0SQAOlAKniuJCAAQAWV2tQAMnAdjzgDyRAAKACUyB5whENx59PZnJM3OwPIACpRYSKxRKRPLZTyALwAPh59lMUAQAG4Vez2RonlQtbZ7DyIGgAFbygUSYWirUAMh1esYBuw9udUB9vqsIh5GBIPNNloV1xMjoA9LmeQB3ODHBUQQs8nApyWCiBsRYPNAVNgVBA8kx6yjshNJ02prNKnPs3IgBomEhwaBJBoABisACYAKwAdisM5A9KAA))

Reviewed By: SamChou19815

Differential Revision: D67529686

fbshipit-source-id: 3a4184cda40d1ddf1baec68d92b00fb5c55fec07

src/typing/errors/error_message.ml

@@ -2915,6 +2915,7 @@ let friendly_message_of_msg = function
 
 let defered_in_speculation = function
   | EUntypedTypeImport _
+  | EMethodUnbinding _
   | EUntypedImport _
   | ENonstrictImport _
   | EUnclearType _

tests/method_unbinding/complex_types.js

@@ -22,10 +22,10 @@ declare var c : I & K;
 declare var c2 : K & I;
 declare var d : I | K;
 
-c.m; // ok
+c.m; // error -- picking I.m
 c2.m; // ok
 d.m; // err
 
-let {m : mc} = c; // ok
+let {m : mc} = c; // err -- picking I.m
 let {m : mc2} = c2; // ok
 let {m : md} = d; // err

tests/method_unbinding/method_unbinding.exp

@@ -1,23 +1,16 @@
-Error -------------------------------------------------------------------------------------------- complex_types.js:12:1
+Error -------------------------------------------------------------------------------------------- complex_types.js:12:3
 
-Cannot get `a.m` because: [incompatible-use]
- - Either property `m` [1] cannot be unbound from the context [2] where it was defined.
- - Or property `m` [1] cannot be unbound from the context [3] where it was defined.
-
-   complex_types.js:12:1
-   12| a.m; // err
-       ^^^
+Cannot get `a.m` because property `m` [1] cannot be unbound from the context [2] where it was defined.
+[method-unbinding]
 
-References:
    complex_types.js:12:3
    12| a.m; // err
          ^ [1]
+
+References:
    complex_types.js:2:5
     2|     m() : void
            ^^^^^^^^^^ [2]
-   complex_types.js:6:5
-    6|     m() : void
-           ^^^^^^^^^^ [3]
 
 
 Error -------------------------------------------------------------------------------------------- complex_types.js:13:3
@@ -52,9 +45,7 @@ References:
 
 Error -------------------------------------------------------------------------------------------- complex_types.js:14:6
 
-All branches are incompatible: [incompatible-use]
- - Either property `m` [1] cannot be unbound from the context [2] where it was defined.
- - Or property `m` [1] cannot be unbound from the context [3] where it was defined.
+property `m` [1] cannot be unbound from the context [2] where it was defined. [method-unbinding]
 
    complex_types.js:14:6
    14| let {m : ma} = a; // err
@@ -64,9 +55,6 @@ References:
    complex_types.js:2:5
     2|     m() : void
            ^^^^^^^^^^ [2]
-   complex_types.js:6:5
-    6|     m() : void
-           ^^^^^^^^^^ [3]
 
 
 Error -------------------------------------------------------------------------------------------- complex_types.js:15:6
@@ -97,6 +85,21 @@ References:
            ^^^^^^^^^^ [2]
 
 
+Error -------------------------------------------------------------------------------------------- complex_types.js:25:3
+
+Cannot get `c.m` because property `m` [1] cannot be unbound from the context [2] where it was defined.
+[method-unbinding]
+
+   complex_types.js:25:3
+   25| c.m; // error -- picking I.m
+         ^ [1]
+
+References:
+   complex_types.js:2:5
+    2|     m() : void
+           ^^^^^^^^^^ [2]
+
+
 Error -------------------------------------------------------------------------------------------- complex_types.js:27:3
 
 Cannot get `d.m` because property `m` [1] cannot be unbound from the context [2] where it was defined.
@@ -112,6 +115,20 @@ References:
            ^^^^^^^^^^ [2]
 
 
+Error -------------------------------------------------------------------------------------------- complex_types.js:29:6
+
+property `m` [1] cannot be unbound from the context [2] where it was defined. [method-unbinding]
+
+   complex_types.js:29:6
+   29| let {m : mc} = c; // err -- picking I.m
+            ^ [1]
+
+References:
+   complex_types.js:2:5
+    2|     m() : void
+           ^^^^^^^^^^ [2]
+
+
 Error -------------------------------------------------------------------------------------------- complex_types.js:31:6
 
 property `m` [1] cannot be unbound from the context [2] where it was defined. [method-unbinding]
@@ -447,4 +464,4 @@ Cannot assign function to `b.m` because property `m` is not writable. [cannot-wr
 
 
 
-Found 30 errors
+Found 32 errors