Cleanup doc and lint warnings.

This CL fixes up several documentation and linter warnings.

Change-Id: Ic367ba1937f20dfe47a8c8e4035c17e8a3d0f2e8
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/17880
Reviewed-by: Ryan Harrison <rharrison@chromium.org>

src/reader/wgsl/parser_impl.cc

diff --git a/src/reader/wgsl/parser_impl.cc b/src/reader/wgsl/parser_impl.cc
index eb66cd2..1b71bea 100644
--- a/src/reader/wgsl/parser_impl.cc
+++ b/src/reader/wgsl/parser_impl.cc
@@ -372,7 +372,7 @@
   std::tie(name, type) = variable_ident_decl();
   if (has_error())
     return nullptr;
-  if (name == "" || type == nullptr) {
+  if (name.empty() || type == nullptr) {
     set_error(peek(), "error parsing constant variable identifier");
     return nullptr;
   }
@@ -593,7 +593,7 @@
   std::tie(name, type) = variable_ident_decl();
   if (has_error())
     return nullptr;
-  if (name == "" || type == nullptr) {
+  if (name.empty() || type == nullptr) {
     set_error(peek(), "invalid identifier declaration");
     return nullptr;
   }
@@ -1102,7 +1102,7 @@
   std::tie(name, type) = variable_ident_decl();
   if (has_error())
     return nullptr;
-  if (name == "" || type == nullptr) {
+  if (name.empty() || type == nullptr) {
     set_error(peek(), "invalid identifier declaration");
     return nullptr;
   }
@@ -1283,7 +1283,7 @@
   std::tie(name, type) = variable_ident_decl();
   if (has_error())
     return {};
-  if (name == "" || type == nullptr)
+  if (name.empty() || type == nullptr)
     return {};
 
   for (;;) {
@@ -1300,7 +1300,7 @@
     std::tie(name, type) = variable_ident_decl();
     if (has_error())
       return {};
-    if (name == "" || type == nullptr) {
+    if (name.empty() || type == nullptr) {
       set_error(t, "found , but no variable declaration");
       return {};
     }
@@ -1683,7 +1683,7 @@
     std::tie(name, type) = variable_ident_decl();
     if (has_error())
       return nullptr;
-    if (name == "" || type == nullptr) {
+    if (name.empty() || type == nullptr) {
       set_error(peek(), "unable to parse variable declaration");
       return nullptr;
     }