PreParsing inner funcs: make scope analysis even more complete.

This adds tracking the following:
- Let / var declarations in for loops

BUG=v8:5501, v8:5516

Review-Url: https://codereview.chromium.org/2616393002
Cr-Commit-Position: refs/heads/master@{#42169}

src/parsing/preparser.h

@@ -1271,6 +1271,11 @@ class PreParser : public ParserBase<PreParser> {
   V8_INLINE PreParserStatement
   BuildInitializationBlock(DeclarationParsingResult* parsing_result,
                            ZoneList<const AstRawString*>* names, bool* ok) {
+    for (auto declaration : parsing_result->declarations) {
+      DeclareAndInitializeVariables(PreParserStatement::Default(),
+                                    &(parsing_result->descriptor), &declaration,
+                                    names, ok);
+    }
     return PreParserStatement::Default();
   }
 

test/cctest/test-parsing.cc

@@ -8865,16 +8865,22 @@ TEST(NoPessimisticContextAllocation) {
        false},
       {"function inner() { for (var {a, my_var} in {}) { } my_var; }", false},
       {"function inner() { for (var {a, my_var} of []) { } my_var; }", false},
-      {"function inner() { class my_var {}; my_var }", false},
-      // In the following cases we still context allocate pessimistically:
-      {"function inner() { function my_var() {} my_var; }", true},
-      {"function inner() { if (true) { function my_var() {} }  my_var; }",
-       true},
       {"function inner() { for (let my_var = 0; my_var < 1; ++my_var) { my_var "
        "} }",
-       true},
+       false},
+      {"function inner() { for (var my_var = 0; my_var < 1; ++my_var) { my_var "
+       "} }",
+       false},
       {"function inner() { for (let a = 0, my_var = 0; my_var < 1; ++my_var) { "
        "my_var } }",
+       false},
+      {"function inner() { for (var a = 0, my_var = 0; my_var < 1; ++my_var) { "
+       "my_var } }",
+       false},
+      {"function inner() { class my_var {}; my_var }", false},
+      // In the following cases we still context allocate pessimistically:
+      {"function inner() { function my_var() {} my_var; }", true},
+      {"function inner() { if (true) { function my_var() {} }  my_var; }",
        true},
   };