Support let, const, and enhanced object literals in StripCode

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=182793727

src/com/google/javascript/jscomp/StripCode.java

@@ -108,6 +108,8 @@ private class Strip extends AbstractPostOrderCallback {
     public void visit(NodeTraversal t, Node n, Node parent) {
       switch (n.getToken()) {
         case VAR:
+        case CONST:
+        case LET:
           removeVarDeclarationsByNameOrRvalue(t, n, parent);
           break;
 
@@ -148,19 +150,18 @@ public void visit(NodeTraversal t, Node n, Node parent) {
     }
 
     /**
-     * Removes declarations of any variables whose names are strip names or
-     * whose whose r-values are static method calls on strip types. Builds a set
-     * of removed variables so that all references to them can be removed.
+     * Removes declarations of any variables whose names are strip names or whose whose r-values are
+     * static method calls on strip types. Builds a set of removed variables so that all references
+     * to them can be removed.
      *
      * @param t The traversal
-     * @param n A VAR node
+     * @param n A VAR, CONST, or LET node
      * @param parent {@code n}'s parent
      */
-    void removeVarDeclarationsByNameOrRvalue(NodeTraversal t, Node n,
-        Node parent) {
+    void removeVarDeclarationsByNameOrRvalue(NodeTraversal t, Node n, Node parent) {
       Node next = null;
-      for (Node nameNode = n.getFirstChild(); nameNode != null;
-          nameNode = next) {
+      // TODO(b/72223678): handle destructuring declarations below.
+      for (Node nameNode = n.getFirstChild(); nameNode != null; nameNode = next) {
         next = nameNode.getNext();
         String name = nameNode.getString();
         if (isStripName(name)
@@ -190,6 +191,8 @@ void maybeRemoveReferenceToRemovedVariable(NodeTraversal t, Node n,
                                                Node parent) {
       switch (parent.getToken()) {
         case VAR:
+        case CONST:
+        case LET:
           // This is a variable declaration, not a reference.
           break;
 
@@ -382,14 +385,22 @@ void eliminateKeysWithStripNamesFromObjLit(NodeTraversal t, Node n) {
       //   ...
       Node key = n.getFirstChild();
       while (key != null) {
-        if (isStripName(key.getString())) {
-          Node next = key.getNext();
-          n.removeChild(key);
-          NodeUtil.markFunctionsDeleted(key, compiler);
-          key = next;
-          compiler.reportChangeToEnclosingScope(n);
-        } else {
-          key = key.getNext();
+        switch (key.getToken()) {
+          case GETTER_DEF:
+          case SETTER_DEF:
+          case STRING_KEY:
+          case MEMBER_FUNCTION_DEF:
+            if (isStripName(key.getString())) {
+              Node next = key.getNext();
+              n.removeChild(key);
+              NodeUtil.markFunctionsDeleted(key, compiler);
+              key = next;
+              compiler.reportChangeToEnclosingScope(n);
+              break;
+            }
+            // fall through
+          default:
+            key = key.getNext();
         }
       }
     }

test/com/google/javascript/jscomp/StripCodeTest.java

@@ -121,6 +121,33 @@ public void testLoggerDefinedInPrototype5() {
          "}");
   }
 
+  public void testLoggerDefinedInPrototype6() {
+    test(
+        lines(
+            "var a = {};",
+            "a.b = function() {};",
+            "a.b.prototype = { ",
+            "  logger(a) {this.x = goog.debug.Logger.getLogger('a.b.c')}",
+            "}"),
+        "var a = {}; a.b = function() {}; a.b.prototype = {}");
+  }
+
+  public void testLoggerDefinedInPrototype7() {
+    test(
+        lines(
+            "var a = {};",
+            "a.b = function() {};",
+            "a.b.prototype = { ",
+            "  ['logger']: goog.debug.Logger.getLogger('a.b.c')",
+            "}"),
+        lines(
+            "var a = {};",
+            "a.b = function() {};",
+            "a.b.prototype = { ",
+            "  ['logger']: null",
+            "}"));
+  }
+
   public void testLoggerDefinedStatically() {
     test("a.b.c = function() {};" +
          "a.b.c.logger = goog.debug.Logger.getLogger('a.b.c');",
@@ -169,6 +196,35 @@ public void testLoggerDefinedInObjectLiteral4() {
          "};");
   }
 
+  public void testLoggerDefinedInObjectLiteral5() {
+    test(
+        lines(
+            "var a = {};",
+            "a.b = {",
+            "  x: 0,",
+            "  logger() { return goog.debug.Logger.getLogger('a.b.c'); }",
+            "};"),
+        "var a = {}; a.b={x:0}");
+  }
+
+  public void testLoggerDefinedInObjectLiteral6() {
+    test(
+        lines(
+            "var a = {};",
+            "a.b = {",
+            "  x: 0,",
+            "  ['logger']: goog.debug.Logger.getLogger('a.b.c')",
+            "};",
+            "a.b['logger']();"),
+        lines(
+            "var a = {};",
+            "a.b = {",
+            "  x: 0,",
+            "  ['logger']: null", // Don't strip computed properties
+            "};",
+            "a.b['logger']()"));
+  }
+
   public void testLoggerDefinedInPrototypeAndUsedInConstructor() {
     test("a.b.c = function(level) {" +
          "  if (!this.logger.isLoggable(level)) {" +
@@ -197,6 +253,14 @@ public void testLoggerVarDeclaration() {
     test("var logger = opt_logger || goog.debug.LogManager.getRoot();", "");
   }
 
+  public void testLoggerLetDeclaration() {
+    test("let logger = opt_logger || goog.debug.LogManager.getRoot();", "");
+  }
+
+  public void testLoggerConstDeclaration() {
+    test("const logger = opt_logger || goog.debug.LogManager.getRoot();", "");
+  }
+
   public void testLoggerMethodCallByVariableType() {
     test("var x = goog.debug.Logger.getLogger('a.b.c'); y.info(a); x.info(a);",
          "y.info(a)");
@@ -400,17 +464,17 @@ public void testReportErrorOnStripInNestedAssignment() {
          StripCode.STRIP_ASSIGNMENT_ERROR);
   }
 
-  public void testNewOperatior1() {
+  public void testNewOperator1() {
     test("function foo() {} foo.bar = new goog.debug.Logger();",
          "function foo() {} foo.bar = null;");
   }
 
-  public void testNewOperatior2() {
+  public void testNewOperator2() {
     test("function foo() {} foo.bar = (new goog.debug.Logger()).foo();",
          "function foo() {} foo.bar = null;");
   }
 
-  public void testNewOperatior3() {
+  public void testNewOperator3() {
     test("(new goog.debug.Logger()).foo().bar = 2;",
          "2;");
   }