bind-gen: Change the order of SymbolDefinitionNodes

It turned out that we'd better sort SymbolDefinitionNodes in
order of their first appearance rather than the alphabetical
order of their names.  In code reading, alphabetic order
doesn't make any sense nor doesn't help read code.  The
order of first use makes more sense.

For example, given |f(B, A, C)|,
  A
  B
  C
  f(B, A, C)
will be changed to
  B
  A
  C
  f(B, A, C)

Bug: 839389
Change-Id: Id6bc57ed4ea0afa6e630ab33a55c5472377927e5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1876293
Commit-Queue: Yuki Shiino <yukishiino@chromium.org>
Reviewed-by: Hitoshi Yoshida <peria@chromium.org>
Cr-Commit-Position: refs/heads/master@{#708950}

third_party/blink/renderer/bindings/scripts/bind_gen/code_node.py

@@ -58,8 +58,10 @@ class CodeNode(object):
 
         def __init__(self):
             # Symbols used in generated code, but not yet defined.  See also
-            # SymbolNode.
-            self.undefined_code_symbols = set()
+            # SymbolNode.  Code symbols are accumulated in order from the first
+            # appearance to the last.  This order affects the insertion order of
+            # SymbolDefinitionNodes at SymbolScopeNode.
+            self.undefined_code_symbols = []
 
     class _LooseFormatter(string.Formatter):
         def get_value(self, key, args, kwargs):
@@ -294,7 +296,8 @@ class CodeNode(object):
         """Receives a report of use of an undefined symbol node."""
         assert isinstance(symbol_node, SymbolNode)
         state = self.current_render_state
-        state.undefined_code_symbols.add(symbol_node)
+        if symbol_node not in state.undefined_code_symbols:
+            state.undefined_code_symbols.append(symbol_node)
 
     def likeliness_of_undefined_code_symbol_usage(self, symbol_node):
         """
@@ -544,11 +547,7 @@ class SymbolScopeNode(SequenceNode):
         self._registered_code_symbols = set()
 
     def _render(self, renderer, last_render_state):
-        # Sort nodes in order to render reproducible results.
-        symbol_nodes = sorted(
-            last_render_state.undefined_code_symbols,
-            key=lambda symbol_node: symbol_node.name)
-        for symbol_node in symbol_nodes:
+        for symbol_node in last_render_state.undefined_code_symbols:
             if (self.is_code_symbol_registered(symbol_node)
                     and not self.is_code_symbol_defined(symbol_node)):
                 self._insert_symbol_definition(symbol_node)