[wasm] Support undefined indirect table entries, behind a flag.

test/mjsunit/wasm/wasm-constants.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.
 
 // Flags: --expose-wasm
 
 function bytes() {
   var buffer = new ArrayBuffer(arguments.length);
   var view = new Uint8Array(buffer);
   for (var i = 0; i < arguments.length; i++) {
@@ skipping 46 matching lines @@
 var kDeclGlobals = 0x03;
 var kDeclDataSegments = 0x04;
 var kDeclFunctionTable = 0x05;
 var kDeclEnd = 0x06;
 var kDeclStartFunction = 0x07;
 var kDeclImportTable = 0x08;
 var kDeclExportTable = 0x09;
 var kDeclFunctionSignatures = 0x0a;
 var kDeclFunctionBodies = 0x0b;
 var kDeclNames = 0x0c;
+var kDeclFunctionTablePad = 0x0d;
 
 var kArity0 = 0;
 var kArity1 = 1;
 var kArity2 = 2;
 var kArity3 = 3;
 var kWasmFunctionTypeForm = 0x40;
 
 var section_names = [
   "memory", "type", "old_function", "global", "data",
   "table", "end", "start", "import", "export",
-  "function", "code", "name"];
+  "function", "code", "name", "table_pad"];
 
 // Function declaration flags
 var kDeclFunctionName   = 0x01;
 var kDeclFunctionImport = 0x02;
 var kDeclFunctionLocals = 0x04;
 var kDeclFunctionExport = 0x08;
 
 // Local types
 var kAstStmt = 0;
 var kAstI32 = 1;
@@ skipping 237 matching lines @@
       }
       threwException = false;
     } catch (e) {
       assertEquals("object", typeof e);
       assertEquals(kTrapMsgs[trap], e.message);
       // Success.
       return;
     }
     throw new MjsUnitAssertionError("Did not trap, expected: " + kTrapMsgs[trap]);
 }