PY-21519 Re-enable proper completion in type comments

Since it's no longer clear under which circumstances the original
problem for which the corresponding check was introduced occurred,
and I wan't able to reproduce it, I revert it temporarily to see whether
it's still worth keeping.

python/src/com/jetbrains/python/codeInsight/typing/PyTypingAnnotationInjector.java

@@ -15,7 +15,6 @@
  */
 package com.jetbrains.python.codeInsight.typing;
 
-import com.intellij.codeInsight.completion.CompletionUtil;
 import com.intellij.lang.Language;
 import com.intellij.lang.injection.MultiHostRegistrar;
 import com.intellij.openapi.util.TextRange;
@@ -80,7 +79,7 @@ public class PyTypingAnnotationInjector extends PyInjectorBase {
       if (annotationText != null) {
         final int start = m.start(1);
         final int end = m.end(1);
-        if (start < end && allowInjectionInComment(host)) {
+        if (start < end) {
           final Language language;
           if ("ignore".equals(annotationText)) {
             language = null;
@@ -111,10 +110,4 @@ public class PyTypingAnnotationInjector extends PyInjectorBase {
   private static boolean isTypingAnnotation(@NotNull String s) {
     return RE_TYPING_ANNOTATION.matcher(s).matches();
   }
-
-  private static boolean allowInjectionInComment(@NotNull PsiLanguageInjectionHost host) {
-    // XXX: Don't inject PyDocstringLanguage during completion inside comments due to an exception related to finding ShredImpl's
-    // hostElementPointer
-    return CompletionUtil.getOriginalOrSelf(host) == host;
-  }
 }

python/testData/completion/typeComment.py

@@ -0,0 +1,3 @@
+import typing
+
+a = []  # type: typing.<caret>

python/testSrc/com/jetbrains/python/PythonCompletionTest.java

@@ -1136,6 +1136,13 @@ public class PythonCompletionTest extends PyTestCase {
     assertDoesntContain(suggested, "_T", "_KT");
   }
 
+  // PY-21519
+  public void testTypeComment() {
+    myFixture.copyFileToProject("../typing/typing.py");
+    final List<String> variants = doTestByFile();
+    assertContainsElements(variants, "List", "Union", "Optional");
+  }
+
   @Override
   protected String getTestDataPath() {
     return super.getTestDataPath() + "/completion";