RollICU to 84fb34e2d to update tz2020b

https://chromium.googlesource.com/chromium/deps/icu.git/+log/aba3f0d..84fb34e2d

84fb34e Revert "Set icu_disable_thin_archive on non-component chromeos builds"
c18a117 Update IANA timezone db to 2020b
146cb61 Set icu_disable_thin_archive on non-component chromeos builds

Update IANA timezone db to 2020b

https://mm.icann.org/pipermail/tz-announce/2020-October/000059.html
     Revised predictions for Morocco's changes starting in 2023.
     Canada's Yukon changes to -07 on 2020-11-01, not 2020-03-08.
     Macquarie Island has stayed in sync with Tasmania since 2011.
     Casey, Antarctica is at +08 in winter and +11 in summer.
     zic no longer supports -y, nor the TYPE field of Rules.

The tz-related files are updated by running update_tz.sh and ICU
data files are rebuilt.

Either in JS console in Chrome or v8 should work like these:
// a) Canada's Yukon changes to -07 on 2020-11-01, not 2020-03-08.
df1 = new Intl.DateTimeFormat("en", {timeZone: "America/Dawson", timeStyle: "long", dateStyle: "long"})
d1 = new Date("2020-03-09T00:00:00.000Z")
df1.format(d1)

Before change
"March 8, 2020 at 5:00:00 PM MST"

After change
"March 8, 2020 at 5:00:00 PM PDT"

Notice "This change affects only the time zone abbreviation (MST vs PDT)
and daylight saving flag for the period between the two dates."

// b) Casey Station, Antarctica  using +08 in winter and +11 in summer since 2018.
df2 = new Intl.DateTimeFormat("en", {timeZone: "Antarctica/Casey", timeStyle: "long", dateStyle: "long"})
d2 = new Date("2020-10-04T00:00:00.000Z")
df2.format(d2)

Before change
"October 4, 2020 at 8:00:00 AM GMT+8"

After change
"October 4, 2020 at 11:00:00 AM GMT+11"

// c) Macquarie Island in sync with Tasmania since 2011.
df3 = new Intl.DateTimeFormat("en", {timeZone: "Antarctica/Macquarie", timeStyle: "long", dateStyle: "long"})

d3 = new Date("2020-04-05T00:00:00.000Z")
df3.format(d3)

Before change
"April 5, 2020 at 11:00:00 AM GMT+11"

After change
"April 5, 2020 at 10:00:00 AM GMT+10"

TBR=jshin@chromium.org

Bug: chromium:1137864
Change-Id: Ic182e359d1bab7bf309a13286cbea4f58b6dda74
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2468382
Commit-Queue: Frank Tang <ftang@chromium.org>
Reviewed-by: Frank Tang <ftang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#816887}

DEPS

@@ -1036,7 +1036,7 @@ deps = {
     Var('chromium_git') + '/chromium/deps/hunspell_dictionaries.git' + '@' + '18e09b9197a3b1d771c077c530d1a4ebad04c167',
 
   'src/third_party/icu':
-    Var('chromium_git') + '/chromium/deps/icu.git' + '@' + 'aba3f0dfeeddc0c69730ec28ef423543b8a62693',
+    Var('chromium_git') + '/chromium/deps/icu.git' + '@' + '84fb34e2d110871c3414183b9f6c0745453b02ad',
 
   'src/third_party/icu4j': {
       'packages': [