[Wasm] Convert many of the fixed-size values to LEB128.

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

 // Copyright 2016 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.
 
 function StringRef(string) {
     this.pos = -1;
     this.string = string;
 }
 
 function DataRef(data) {
@@ skipping 146 matching lines @@
         emit_u8(bytes, this.memory.exp ? 1 : 0);
     }
 
     // Add signatures section
     if (this.signatures.length > 0) {
         if (debug) print("emitting signatures @ " + bytes.length);
         emit_u8(bytes, kDeclSignatures);
         emit_varint(bytes, this.signatures.length);
         for (sig of this.signatures) {
             var params = sig.length - 1;
-            emit_u8(bytes, params);
+            emit_varint(bytes, params);
             for (var j = 0; j < sig.length; j++) {
                 emit_u8(bytes, sig[j]);
             }
         }
     }
 
     // Add imports section
     if (this.imports.length > 0) {
         if (debug) print("emitting imports @ " + bytes.length);
         emit_u8(bytes, kDeclImportTable);
         emit_varint(bytes, this.imports.length);
         for (imp of this.imports) {
-            emit_u16(bytes, imp.sig_index);
+            emit_varint(bytes, imp.sig_index);
             emit_string(bytes, imp.module);
             if (imp.name == undefined) {
               emit_u32(bytes, 0);
             } else {
               emit_string(bytes, imp.name);
             }
         }
     }
 
     // Add functions section
@@ skipping 30 matching lines @@
               if (l.i64_count > 0) {
                 local_decls.push({count: l.i64_count, type: kAstI64});
               }
               if (l.f32_count > 0) {
                 local_decls.push({count: l.f32_count, type: kAstF32});
               }
               if (l.f64_count > 0) {
                 local_decls.push({count: l.f64_count, type: kAstF64});
               }
             }
-            emit_u8(bytes, local_decls.length);
+            emit_varint(bytes, local_decls.length);
             for (decl of local_decls) {
               emit_varint(bytes, decl.count);
               emit_u8(bytes, decl.type);
             }
 
             for (var i = 0; i < func.body.length; i++) {
                 emit_u8(bytes, func.body[i]);
             }
             var length = bytes.length - length_pos - 2;
             bytes[length_pos] = length & 0xff;
             bytes[length_pos + 1] = (length >> 8) & 0xff;
 
             index++;
         }
     }
 
     // Add start function section.
     if (this.start_index != undefined) {
         if (debug) print("emitting start function @ " + bytes.length);
       emit_u8(bytes, kDeclStartFunction);
       emit_varint(bytes, this.start_index);
     }
 
     if (this.function_table.length > 0) {
         if (debug) print("emitting function table @ " + bytes.length);
         emit_u8(bytes, kDeclFunctionTable);
         emit_varint(bytes, this.function_table.length);
         for (index of this.function_table) {
-            emit_u16(bytes, index);
+            emit_varint(bytes, index);
         }
     }
 
     if (exports > 0) {
         if (debug) print("emitting exports @ " + bytes.length);
         emit_u8(bytes, kDeclExportTable);
         emit_varint(bytes, exports);
         for (func of this.functions) {
             for (exp of func.exports) {
-                emit_u16(bytes, func.index);
+                emit_varint(bytes, func.index);
                 emit_string(bytes, exp);
             }
         }
     }
 
     if (this.data_segments.length > 0) {
         if (debug) print("emitting data segments @ " + bytes.length);
         emit_u8(bytes, kDeclDataSegments);
         emit_varint(bytes, this.data_segments.length);
         for (seg of this.data_segments) {
@@ skipping 86 matching lines @@
 }
 
 WasmModuleBuilder.prototype.instantiate = function(ffi, memory) {
     var buffer = this.toBuffer();
     if (memory != undefined) {
       return Wasm.instantiateModule(buffer, ffi, memory);
     } else {
       return Wasm.instantiateModule(buffer, ffi);
     }
 }