[WASM] Implements catch for the wasm low level exception mechanism.

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 126 matching lines @@
 var kExprBlock = 0x01;
 var kExprLoop = 0x02;
 var kExprIf = 0x03;
 var kExprElse = 0x04;
 var kExprSelect = 0x05;
 var kExprBr = 0x06;
 var kExprBrIf = 0x07;
 var kExprBrTable = 0x08;
 var kExprReturn = 0x09;
 var kExprThrow = 0xfa;
+var kExprTry = 0xfb;
+var kExprCatch = 0xfe;
 var kExprEnd = 0x0f;
 var kExprTeeLocal = 0x19;
 var kExprDrop = 0x0b;
 
 var kExprI32Const = 0x10;
 var kExprI64Const = 0x11;
 var kExprF64Const = 0x12;
 var kExprF32Const = 0x13;
 var kExprGetLocal = 0x14;
 var kExprSetLocal = 0x15;
@@ skipping 203 matching lines @@
         eval(code);
       }
     } catch (e) {
       assertEquals("number", typeof e);
       assertEquals(value, e);
       // Success.
       return;
     }
     throw new MjsUnitAssertionError("Did not throw at all, expected: " + value);
 }