fix handling of imports

Summary:
All imports are treated as "type" definitions regardless of whether or not they have a "type" kind. You can import classes and enums as values and use them in type locations. Additionally namespace imports can be used in a type location (eg `React.MixedElement`).

Because we don't have cross-file information, we cannot statically determine if an imported thing is a "type referencible" thing, so we have to just treat all imports as possible types.

This diff marks all import bindings as type definitions.

Reviewed By: evanyeung

Differential Revision: D33574248

fbshipit-source-id: b6dc10dc2afb8ad01e0dbfbe40d0dab25b0ec297

Author: bradzacher

tools/hermes-parser/js/hermes-eslint/__tests__/HermesScopeManager-test.js

@@ -1600,7 +1600,7 @@ describe('Imports', () => {
               {
                 name: 'RefType',
                 type: DefinitionType.ImportBinding,
-                referenceCount: 0,
+                referenceCount: 1,
               },
               {
                 name: 'foo',
@@ -1717,7 +1717,7 @@ describe('Imports', () => {
                 {
                   name: 'RefType',
                   type: DefinitionType.ImportBinding,
-                  referenceCount: 0,
+                  referenceCount: 1,
                 },
                 {
                   name: 'foo',
@@ -1835,7 +1835,7 @@ describe('Imports', () => {
             {
               name: 'RefType',
               type: DefinitionType.ImportBinding,
-              referenceCount: 0,
+              referenceCount: 1,
             },
             {
               name: 'foo',

tools/hermes-parser/js/hermes-eslint/src/scope-manager/definition/ImportBindingDefinition.js

@@ -43,33 +43,31 @@ class ImportBindingDefinition extends DefinitionBase<
           decl.importKind === 'type' ||
           decl.importKind === 'typeof'
         ) {
-          this.isTypeDefinition = true;
           this.isVariableDefinition = false;
         } else {
-          this.isTypeDefinition = false;
           this.isVariableDefinition = true;
         }
         break;
 
       case 'ImportDefaultSpecifier':
         if (decl.importKind === 'type' || decl.importKind === 'typeof') {
-          this.isTypeDefinition = true;
           this.isVariableDefinition = false;
         } else {
-          this.isTypeDefinition = false;
           this.isVariableDefinition = true;
         }
         break;
 
       case 'ImportNamespaceSpecifier':
-        // not possible for a namespace import to be a type in flow
-        this.isTypeDefinition = false;
         this.isVariableDefinition = true;
         break;
     }
   }
 
-  +isTypeDefinition: boolean;
+  // all imports are treated as "type" definitions regardless of whether or
+  // not they have a "type" kind. You can import classes and enums as values
+  // and use them in type locations. Additionally namespace imports can be
+  // used in a type location (eg React.MixedElement).
+  +isTypeDefinition: boolean = true;
   +isVariableDefinition: boolean;
 }