Fix unnecessary parenthesis around 'this' in refactorings

Operator priority calculation for 'this' expressions was incorrect in
JetPsiUtil.getPriority(): it would return a very low value for
a JetThisExpression, causing the IDE to report that parenthesis
are necessary in an expression like '(this)[1]'.

Fix this by making JetThisExpression not implement
JetStatementExpression by removing the implements clause from
JetLabelQualifiedInstanceExpression and adding it to all other
subclasses of JetLabelQualifiedInstanceExpression.

Fixes KT-4513.

compiler/frontend/src/org/jetbrains/jet/lang/psi/JetLabelQualifiedInstanceExpression.java

@@ -20,8 +20,7 @@ import com.intellij.lang.ASTNode;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.jet.JetNodeTypes;
 
-public abstract class JetLabelQualifiedInstanceExpression extends JetLabelQualifiedExpression
+public abstract class JetLabelQualifiedInstanceExpression extends JetLabelQualifiedExpression {
-        implements JetStatementExpression {
 
     public JetLabelQualifiedInstanceExpression(@NotNull ASTNode node) {
         super(node);

compiler/frontend/src/org/jetbrains/jet/lang/psi/JetSuperExpression.java

@@ -21,7 +21,7 @@ import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.jetbrains.jet.JetNodeTypes;
 
-public class JetSuperExpression extends JetLabelQualifiedInstanceExpression {
+public class JetSuperExpression extends JetLabelQualifiedInstanceExpression implements JetStatementExpression {
 
     public JetSuperExpression(@NotNull ASTNode node) {
         super(node);

idea/testData/intentions/removeUnnecessaryParentheses/unnecessaryParentheses8.kt

@@ -0,0 +1,6 @@
+class C() {
+    fun get(i: Int) = i + 1
+
+    // KT-4513: Unnecessary parenthesis around 'this'
+    val foo = (th<caret>is)[41]
+}

idea/testData/intentions/removeUnnecessaryParentheses/unnecessaryParentheses8.kt.after

@@ -0,0 +1,6 @@
+class C() {
+    fun get(i: Int) = i + 1
+
+    // KT-4513: Unnecessary parenthesis around 'this'
+    val foo = this[41]
+}

idea/tests/org/jetbrains/jet/plugin/intentions/CodeTransformationTestGenerated.java

@@ -1176,6 +1176,11 @@ public class CodeTransformationTestGenerated extends AbstractCodeTransformationT
             doTestRemoveUnnecessaryParentheses("idea/testData/intentions/removeUnnecessaryParentheses/unnecessaryParentheses7.kt");
         }
         
+        @TestMetadata("unnecessaryParentheses8.kt")
+        public void testUnnecessaryParentheses8() throws Exception {
+            doTestRemoveUnnecessaryParentheses("idea/testData/intentions/removeUnnecessaryParentheses/unnecessaryParentheses8.kt");
+        }
+        
     }
     
     public static Test suite() {