Reland: change most cases of variable redeclaration from TypeError to SyntaxError.

test/mjsunit/es6/block-eval-var-over-let.js

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Var-let conflict in a function throws, even if the var is in an eval
 
 // Throws at the top level of a function
 assertThrows(function() {
   let x = 1;
   eval('var x');
-}, TypeError);
+}, SyntaxError);
 
 // If the eval is in its own block scope, throws
 assertThrows(function() {
   let y = 1;
   { eval('var y'); }
-}, TypeError);
+}, SyntaxError);
 
 // If the let is in its own block scope, with the eval, throws
 assertThrows(function() {
   {
     let x = 1;
     eval('var x');
   }
-}, TypeError);
+}, SyntaxError);
 
 // Legal if the let is no longer visible
 assertDoesNotThrow(function() {
   {
     let x = 1;
   }
   eval('var x');
 });
 
 // All the same works for const:
 // Throws at the top level of a function
 assertThrows(function() {
   const x = 1;
   eval('var x');
-}, TypeError);
+}, SyntaxError);
 
 // If the eval is in its own block scope, throws
 assertThrows(function() {
   const y = 1;
   { eval('var y'); }
-}, TypeError);
+}, SyntaxError);
 
 // If the const is in its own block scope, with the eval, throws
 assertThrows(function() {
   {
     const x = 1;
     eval('var x');
   }
-}, TypeError);
+}, SyntaxError);
 
 // Legal if the const is no longer visible
 assertDoesNotThrow(function() {
   {
     const x = 1;
   }
   eval('var x');
 });
 
 // In global scope
@@ skipping 67 matching lines @@
     {
       let x = 1;
       eval('{ function x() {} }');
     }
   })();
 } catch (e) {
   caught = true;
 }
 // TODO(littledan): switch to assertTrue when bug is fixed
 assertTrue(caught);