v8: reapply floating patches

Reapply floating patches. Special mention: also reapplies 017009f but
with the extra change of removing DescriptorArray::kTransitionsIndex
from the postmortem metadata generator because said field no longer
exists in V8 3.14.

deps/v8/build/common.gypi

@@ -378,15 +378,6 @@
         'conditions': [
           ['OS=="linux" or OS=="freebsd" or OS=="openbsd" or OS=="netbsd" \
             or OS=="android"', {
-            'cflags!': [
-              '-O2',
-              '-Os',
-            ],
-            'cflags': [
-              '-fdata-sections',
-              '-ffunction-sections',
-              '-O3',
-            ],
             'conditions': [
               [ 'gcc_version==44 and clang==0', {
                 'cflags': [

deps/v8/src/platform-posix.cc

@@ -109,11 +109,20 @@ void* OS::GetRandomMmapAddr() {
     raw_addr &= V8_UINT64_C(0x3ffffffff000);
 #else
     uint32_t raw_addr = V8::RandomPrivate(isolate);
-    // The range 0x20000000 - 0x60000000 is relatively unpopulated across a
-    // variety of ASLR modes (PAE kernel, NX compat mode, etc) and on macos
-    // 10.6 and 10.7.
+
+    // For our 32-bit mmap() hint, we pick a random address in the bottom
+    // half of the top half of the address space (that is, the third quarter).
+    // Because we do not MAP_FIXED, this will be treated only as a hint -- the
+    // system will not fail to mmap() because something else happens to already
+    // be mapped at our random address. We deliberately set the hint high enough
+    // to get well above the system's break (that is, the heap); systems will
+    // either try the hint and if that fails move higher (MacOS and other BSD
+    // derivatives) or try the hint and if that fails allocate as if there were
+    // no hint at all (Linux, Solaris, illumos and derivatives). The high hint
+    // prevents the break from getting hemmed in at low values, ceding half of
+    // the address space to the system heap.
     raw_addr &= 0x3ffff000;
-    raw_addr += 0x20000000;
+    raw_addr += 0x80000000;
 #endif
     return reinterpret_cast<void*>(raw_addr);
   }

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

@@ -78,14 +78,20 @@ consts_misc = [
     { 'name': 'SmiValueShift',          'value': 'kSmiTagSize' },
     { 'name': 'PointerSizeLog2',        'value': 'kPointerSizeLog2' },
 
-    { 'name': 'prop_idx_transitions',
-        'value': 'DescriptorArray::kTransitionsIndex' },
+    { 'name': 'prop_desc_key',
+        'value': 'DescriptorArray::kDescriptorKey' },
+    { 'name': 'prop_desc_details',
+        'value': 'DescriptorArray::kDescriptorDetails' },
+    { 'name': 'prop_desc_value',
+        'value': 'DescriptorArray::kDescriptorValue' },
+    { 'name': 'prop_desc_size',
+        'value': 'DescriptorArray::kDescriptorSize' },
     { 'name': 'prop_idx_first',
         'value': 'DescriptorArray::kFirstIndex' },
     { 'name': 'prop_type_field',
         'value': 'FIELD' },
     { 'name': 'prop_type_first_phantom',
-        'value': 'MAP_TRANSITION' },
+        'value': 'Code::MAP_TRANSITION' },
     { 'name': 'prop_type_mask',
         'value': 'PropertyDetails::TypeField::kMask' },
 
@@ -107,7 +113,7 @@ extras_accessors = [
     'JSObject, elements, Object, kElementsOffset',
     'FixedArray, data, uintptr_t, kHeaderSize',
     'Map, instance_attributes, int, kInstanceAttributesOffset',
-    'Map, instance_descriptors, int, kInstanceDescriptorsOrBitField3Offset',
+    'Map, transitions, uintptr_t, kTransitionsOrBackPointerOffset',
     'Map, inobject_properties, int, kInObjectPropertiesOffset',
     'Map, instance_size, int, kInstanceSizeOffset',
     'HeapNumber, value, double, kValueOffset',