[wasm] Fix -Wsign-compare warnings.

test/unittests/wasm/leb-helper-unittest.cc

Index: test/unittests/wasm/leb-helper-unittest.cc
diff --git a/test/unittests/wasm/leb-helper-unittest.cc b/test/unittests/wasm/leb-helper-unittest.cc
index b9759332bbfde4524fd577ea5901416434e9ce07..ff7bedc4cfcfc2f0dc374c9dc29c0167ae30ec1f 100644
--- a/test/unittests/wasm/leb-helper-unittest.cc
+++ b/test/unittests/wasm/leb-helper-unittest.cc
@@ -23,19 +23,19 @@ TEST_F(LEBHelperTest, sizeof_u32v) {
     EXPECT_EQ(1, LEBHelper::sizeof_u32v(i));
   }
 
-  for (uint32_t i = (1 << 7); i < (1 << 9); i++) {
+  for (uint32_t i = (1u << 7); i < (1u << 9); i++) {
     EXPECT_EQ(2, LEBHelper::sizeof_u32v(i));
   }
 
-  for (uint32_t i = (1 << 14); i < (1 << 16); i += 33) {
+  for (uint32_t i = (1u << 14); i < (1u << 16); i += 33) {
     EXPECT_EQ(3, LEBHelper::sizeof_u32v(i));
   }
 
-  for (uint32_t i = (1 << 21); i < (1 << 24); i += 33999) {
+  for (uint32_t i = (1u << 21); i < (1u << 24); i += 33999) {
     EXPECT_EQ(4, LEBHelper::sizeof_u32v(i));
   }
 
-  for (uint32_t i = (1 << 28); i < (1 << 31); i += 33997779) {
+  for (uint32_t i = (1u << 28); i < (1u << 31); i += 33997779u) {
     EXPECT_EQ(5, LEBHelper::sizeof_u32v(i));
   }