KT-19145: Enable type completion for extension properties

#KT-19145 fixed

idea/idea-completion/src/org/jetbrains/kotlin/idea/completion/BasicCompletionSession.kt

@@ -198,7 +198,7 @@ class BasicCompletionSession(
                 // no auto-popup on typing after "val", "var" and "fun" because it's likely the name of the declaration which is being typed by user
                 if (parameters.invocationCount == 0) {
                     val suppressOtherCompletion = when (declaration) {
-                        is KtNamedFunction -> prefixMatcher.prefix.let { it.isEmpty() || it[0].isLowerCase() /* function name usually starts with lower case letter */ }
+                        is KtNamedFunction, is KtProperty -> prefixMatcher.prefix.let { it.isEmpty() || it[0].isLowerCase() /* function name usually starts with lower case letter */ }
                         else -> true
                     }
                     if (suppressOtherCompletion) return

idea/idea-completion/testData/basic/common/autoPopup/InValExtType.kt

@@ -0,0 +1,6 @@
+class Some
+
+val S<caret>
+
+// INVOCATION_COUNT: 0
+// EXIST: Some

idea/idea-completion/tests/org/jetbrains/kotlin/idea/completion/test/JSBasicCompletionTestGenerated.java

@@ -1075,6 +1075,12 @@ public class JSBasicCompletionTestGenerated extends AbstractJSBasicCompletionTes
                 doTest(fileName);
             }
 
+            @TestMetadata("InValExtType.kt")
+            public void testInValExtType() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("idea/idea-completion/testData/basic/common/autoPopup/InValExtType.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("NoAutoPopupAfterNumberLiteral.kt")
             public void testNoAutoPopupAfterNumberLiteral() throws Exception {
                 String fileName = KotlinTestUtils.navigationMetadata("idea/idea-completion/testData/basic/common/autoPopup/NoAutoPopupAfterNumberLiteral.kt");

idea/idea-completion/tests/org/jetbrains/kotlin/idea/completion/test/JvmBasicCompletionTestGenerated.java

@@ -1075,6 +1075,12 @@ public class JvmBasicCompletionTestGenerated extends AbstractJvmBasicCompletionT
                 doTest(fileName);
             }
 
+            @TestMetadata("InValExtType.kt")
+            public void testInValExtType() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("idea/idea-completion/testData/basic/common/autoPopup/InValExtType.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("NoAutoPopupAfterNumberLiteral.kt")
             public void testNoAutoPopupAfterNumberLiteral() throws Exception {
                 String fileName = KotlinTestUtils.navigationMetadata("idea/idea-completion/testData/basic/common/autoPopup/NoAutoPopupAfterNumberLiteral.kt");