[postmortem] add ScopeInfo and Context types

The metadata introduced in this patch will be useful for postmortem
tools to inspect Contexts and ScopeInfos (see
https://github.com/nodejs/llnode/issues/211).

R=bmeurer@google.com, yangguo@google.com

Change-Id: I927fcab4014d128bd782046c1ecb9ee045723e95
Reviewed-on: https://chromium-review.googlesource.com/1153858Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#54768}

BUILD.gn

@@ -850,6 +850,7 @@ action("postmortem-metadata") {
     "src/objects/js-regexp-string-iterator.h",
     "src/objects/map.h",
     "src/objects/map-inl.h",
+    "src/objects/scope-info.h",
     "src/objects/script.h",
     "src/objects/script-inl.h",
     "src/objects/shared-function-info.h",

tools/gen-postmortem-metadata.py

@@ -58,6 +58,9 @@ consts_misc = [
     { 'name': 'APIObjectType',          'value': 'JS_API_OBJECT_TYPE' },
     { 'name': 'SpecialAPIObjectType',   'value': 'JS_SPECIAL_API_OBJECT_TYPE' },
 
+    { 'name': 'FirstContextType',     'value': 'FIRST_CONTEXT_TYPE' },
+    { 'name': 'LastContextType',     'value': 'LAST_CONTEXT_TYPE' },
+
     { 'name': 'IsNotStringMask',        'value': 'kIsNotStringMask' },
     { 'name': 'StringTag',              'value': 'kStringTag' },
 
@@ -282,7 +285,7 @@ extras_accessors = [
 expected_classes = [
     'ConsString', 'FixedArray', 'HeapNumber', 'JSArray', 'JSFunction',
     'JSObject', 'JSRegExp', 'JSValue', 'Map', 'Oddball', 'Script',
-    'SeqOneByteString', 'SharedFunctionInfo'
+    'SeqOneByteString', 'SharedFunctionInfo', 'ScopeInfo'
 ];