mdb_v8: update for v0.12

Bugs fixed:

* v0.12 and later: in-object properties not printing correctly.
* 64-bit: not printing external strings correctly (offset was hardcoded
for 32-bit). This would happen with "::jsstack -vn0" because the
script "node.js" wasn't printed correctly, at least with 0.10 core
files.
* 64-bit: printing JS source (via "::jsstack -v") emits errors and shows
the wrong code.
* Several build warnings.
* Two-byte strings are unnecessarily truncated.
* Could print friendlier note when given obviously bogus function token
positions.

New features:

* ::jsstack prints much cleaner output by default.
* ::jsprint keys are now quoted.
* ::jsstack -v includes "this" value for each function on the stack.
* ::jsstack -v includes more details about each argument (constructor
names for each object).
* new commands: ::jsconstructor, ::jsfunctions, ::jssource, ::nodebuffer
and ::v8internal.
* ::findjsobjects and ::jsprint hidden flags for developers to measure
and improve test coverage.
* internal jsobj_properties() function is much better documented.

Reviewed-By: Timothy J Fontaine <tjfontaine@gmail.com>

Conflicts:
	deps/mdb_v8/mdb_v8.c
	test/pummel/test-postmortem-details.js

deps/v8/tools/gen-postmortem-metadata.py

@@ -121,6 +121,10 @@
         'value': 'Map::ElementsKindBits::kShift' },
     { 'name': 'bit_field3_dictionary_map_shift',
         'value': 'Map::DictionaryMap::kShift' },
+    { 'name': 'fieldindex_mask',
+        'value': 'PropertyDetails::FieldIndexField::kMask' },
+    { 'name': 'fieldindex_shift',
+        'value': 'PropertyDetails::FieldIndexField::kShift' },
 
     { 'name': 'off_fp_context',
         'value': 'StandardFrameConstants::kContextOffset' },
@@ -146,7 +150,7 @@
     'Map, instance_size, int, kInstanceSizeOffset',
     'Map, bit_field, char, kBitFieldOffset',
     'Map, bit_field2, char, kBitField2Offset',
-    'Map, bit_field3, SMI, kBitField3Offset',
+    'Map, bit_field3, int, kBitField3Offset',
     'Map, prototype, Object, kPrototypeOffset',
     'NameDictionaryShape, prefix_size, int, kPrefixSize',
     'NameDictionaryShape, entry_size, int, kEntrySize',