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

test/mjsunit/wasm/wasm-module-builder.js

Index: test/mjsunit/wasm/wasm-module-builder.js
diff --git a/test/mjsunit/wasm/wasm-module-builder.js b/test/mjsunit/wasm/wasm-module-builder.js
index bfc4460d91b899d4ca640502cbfd625ef35ea1b4..4cdcab8a63059f9171cb44bdfc132117c23d7ca7 100644
--- a/test/mjsunit/wasm/wasm-module-builder.js
+++ b/test/mjsunit/wasm/wasm-module-builder.js
@@ -36,6 +36,7 @@ function WasmModuleBuilder() {
     this.function_table = [];
     this.data_segments = [];
     this.explicit = [];
+    this.pad = null;
     return this;
 }
 
@@ -48,6 +49,11 @@ WasmModuleBuilder.prototype.addMemory = function(min, max, exp) {
     return this;
 }
 
+WasmModuleBuilder.prototype.addPad = function(size) {
+    this.pad = size;
+    return this;
+}
+
 WasmModuleBuilder.prototype.addExplicitSection = function(bytes) {
   this.explicit.push(bytes);
   return this;
@@ -323,6 +329,14 @@ WasmModuleBuilder.prototype.toArray = function(debug) {
         });
     }
 
+    // Add an indirect function table pad section.
+    if (wasm.pad !== null) {
+        if (debug) print("emitting indirect function table pad @ " + bytes.length);
+        emit_section(bytes, kDeclFunctionTablePad, function(bytes) {
+            emit_varint(bytes, wasm.pad);
+        });
+    }
+
     // End the module.
     if (debug) print("emitting end @ " + bytes.length);
     emit_section(bytes, kDeclEnd, function(bytes) {});