fix completion not launching insert handler after explicit common prefix insertion

java/java-tests/testData/codeInsight/completion/normal/AfterCommonPrefix.java

@@ -0,0 +1,5 @@
+public class SomeClass {
+  void foo(String param) {
+    if (param.<caret>)
+  }
+}

java/java-tests/testData/codeInsight/completion/normal/AfterCommonPrefix_after.java

@@ -0,0 +1,5 @@
+public class SomeClass {
+  void foo(String param) {
+    if (param.equals(<caret>))
+  }
+}

java/java-tests/testSrc/com/intellij/codeInsight/completion/NormalCompletionTest.groovy

@@ -858,6 +858,16 @@ public class NormalCompletionTest extends LightFixtureCompletionTestCase {
     assertStringItems("myField1", "myField2");
   }
 
+  public void testAfterCommonPrefix() throws Throwable {
+    configure()
+    type 'eq'
+    assertStringItems("equals", "equalsIgnoreCase");
+    complete()
+    assertStringItems("equals", "equalsIgnoreCase");
+    type '('
+    checkResult()
+  }
+
   public void testClassNameInsideIdentifierInIf() throws Throwable {
     configure()
     type '\n'