Update V8 to r7079 as required by WebKit r80534.

Change-Id: I487c152e485d5a40b68997d7c0d2f1fba5da0834
diff --git a/src/SConscript b/src/SConscript
index c3561be..34ca91c 100755
--- a/src/SConscript
+++ b/src/SConscript
@@ -153,6 +153,7 @@
     arm/jump-target-arm.cc
     arm/lithium-arm.cc
     arm/lithium-codegen-arm.cc
+    arm/lithium-gap-resolver-arm.cc
     arm/macro-assembler-arm.cc
     arm/regexp-macro-assembler-arm.cc
     arm/register-allocator-arm.cc
@@ -233,6 +234,7 @@
   'os:android': ['platform-linux.cc', 'platform-posix.cc'],
   'os:macos':   ['platform-macos.cc', 'platform-posix.cc'],
   'os:solaris': ['platform-solaris.cc', 'platform-posix.cc'],
+  'os:cygwin':  ['platform-cygwin.cc', 'platform-posix.cc'],
   'os:nullos':  ['platform-nullos.cc'],
   'os:win32':   ['platform-win32.cc'],
   'mode:release': [],
@@ -264,6 +266,9 @@
   'os:solaris': [
     'd8-posix.cc'
   ],
+  'os:cygwin': [
+    'd8-posix.cc'
+  ],
   'os:win32': [
     'd8-windows.cc'
   ],