Revert 205109 "Temporarily turn on Blink's partition allocator f..."

Likely candidate for broken incremental linux builds, which are failing with:
<command-line>:0:0: warning: "ENABLE_PARTITION_ALLOC" redefined [enabled by
default]
<command-line>:0:0: note: this is the location of the previous definition

> Temporarily turn on Blink's partition allocator for Linux in order to get full perf runs.
> 
> BUG=246860
> TBR=abarth@chromium.org
> 
> Review URL: https://codereview.chromium.org/16344004

TBR=cevans@chromium.org

Review URL: https://codereview.chromium.org/15864013

git-svn-id: http://src.chromium.org/svn/trunk/src/build@205112 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

common.gypi

@@ -1812,9 +1812,6 @@
       ],
     },
     'conditions': [
-      ['OS=="linux"', {
-        'defines': ['ENABLE_PARTITION_ALLOC=1'],
-      }],
       ['(OS=="mac" or OS=="ios") and asan==1', {
         'dependencies': [
           '<(DEPTH)/build/mac/asan.gyp:asan_dynamic_runtime',