Special prop assignment symbol applies only to lhs

In a Javascript file, the binder assigns a SpecialPropertyAssignment
marker to the BinaryExpression node of several kinds of special
assignments. Then it binds a special symbol whose declaration is that
BinaryExpression node. But the symbol only applies to the left-hand side
of the assignment. The right-hand side is an independent expression that
should have its own symbols.

Previously, symbol lookup in the checker didn't check whether a
Javascript node that was part of a special property assignment came from
the lhs or the rhs. So the right-hand side would also incorrectly get
the special symbol intended for the left-hand side.

`getSpecialPropertyAssignmentSymbolFromEntityName` in the checker now
checks that its argument is the left-hand side of an assignment before
returning a special property assignment symbol.

Author: sandersn

src/compiler/checker.ts

@@ -20898,7 +20898,9 @@ namespace ts {
                 return getSymbolOfNode(entityName.parent);
             }
 
-            if (isInJavaScriptFile(entityName) && entityName.parent.kind === SyntaxKind.PropertyAccessExpression) {
+            if (isInJavaScriptFile(entityName) &&
+                entityName.parent.kind === SyntaxKind.PropertyAccessExpression &&
+                entityName.parent === (entityName.parent.parent as BinaryExpression).left) {
                 // Check if this is a special property assignment
                 const specialPropertyAssignmentSymbol = getSpecialPropertyAssignmentSymbolFromEntityName(entityName);
                 if (specialPropertyAssignmentSymbol) {

tests/cases/fourslash/renameJsObjectLiteralMethod.ts

@@ -0,0 +1,13 @@
+/// <reference path="fourslash.ts"/>
+// @allowJs: true
+// @Filename: a.js
+////const foo = {
+////    set: function (x) {
+////        this._x = x;
+////    },
+////    copy: function ([|x|]) {
+////        this._x = /**/[|x|].prop;
+////    }
+////};
+goTo.marker();
+verify.renameLocations(/*findInStrings*/ false, /*findInComments*/ false);