[cleanup][torque] Replace all std::endl with \n

This CL replaces all std::endl in implementation-visitor
since std::endl flushes the stream (which is not necessary).

R=tebbi@chromium.org

Bug: v8:7754, v8:7793
Change-Id: Ic4b43905280020a99cb405cc90440b2adb679839
Reviewed-on: https://chromium-review.googlesource.com/1142780Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Commit-Queue: Simon Zünd <szuend@google.com>
Cr-Commit-Position: refs/heads/master@{#54546}

src/torque/implementation-visitor.h

@@ -156,14 +156,14 @@ class ImplementationVisitor : public FileVisitor {
         : new_lines_(new_lines), visitor_(visitor) {
       if (new_lines) visitor->GenerateIndent();
       visitor->source_out() << "{";
-      if (new_lines) visitor->source_out() << std::endl;
+      if (new_lines) visitor->source_out() << "\n";
       visitor->indent_++;
     }
     ~ScopedIndent() {
       visitor_->indent_--;
       visitor_->GenerateIndent();
       visitor_->source_out() << "}";
-      if (new_lines_) visitor_->source_out() << std::endl;
+      if (new_lines_) visitor_->source_out() << "\n";
     }
 
    private: