Fix comment typos

Review-Url: https://codereview.chromium.org/2399933005
Cr-Commit-Position: refs/heads/master@{#40066}

src/ast/scopes.cc

@@ -1451,8 +1451,7 @@ void Scope::Print(int n) {
 }
 
 void Scope::CheckScopePositions() {
-  // A scope is allowed to have invalid positions if it is hidden and has no
-  // inner scopes
+  // Visible leaf scopes must have real positions.
   if (!is_hidden() && inner_scope_ == nullptr) {
     CHECK_NE(kNoSourcePosition, start_position());
     CHECK_NE(kNoSourcePosition, end_position());

src/isolate.h

@@ -724,7 +724,7 @@ class Isolate {
   void ReportFailedAccessCheck(Handle<JSObject> receiver);
 
   // Exception throwing support. The caller should use the result
-  // of Throw() as its return vaue.
+  // of Throw() as its return value.
   Object* Throw(Object* exception, MessageLocation* location = NULL);
   Object* ThrowIllegalOperation();