Try yaml template

Author: mdebbar

.cirrus.yml

@@ -1,5 +1,24 @@
 gcp_credentials: ENCRYPTED[987a78af29b91ce8489594c9ab3fec21845bbe5ba68294b8f6def3cf0d380830f06687a89ea69c87344c5ade369700fe]
 
+web_shard_template: &WEB_SHARD_TEMPLATE
+  only_if: "changesInclude('.cirrus.yml', 'lib/web_ui/**', 'web_sdk/**') || $CIRRUS_PR == ''"
+  environment:
+    # As of October 2019, the Web shards needed more than 6G of RAM.
+    CPU: 2
+    MEMORY: 8G
+  compile_host_script: |
+    cd $ENGINE_PATH/src
+    ./flutter/tools/gn --unoptimized --full-dart-sdk
+    ninja -C out/host_debug_unopt
+  fetch_framework_script: |
+    mkdir -p $FRAMEWORK_PATH
+    cd $FRAMEWORK_PATH
+    git clone https://github.com/flutter/flutter.git
+    cd flutter
+    bin/flutter update-packages --local-engine=host_debug_unopt
+  script:
+    - dart --enable-asserts $FRAMEWORK_PATH/flutter/dev/bots/test.dart --local-engine=host_debug_unopt
+
 # LINUX
 task:
   gke_container:
@@ -178,23 +197,7 @@ task:
         - dart --enable-asserts $FRAMEWORK_PATH/flutter/dev/bots/test.dart --local-engine=host_debug_unopt
 
     - name: web_tests-5-linux
-      only_if: "changesInclude('.cirrus.yml', 'lib/web_ui/**', 'web_sdk/**') || $CIRRUS_PR == ''"
-      environment:
-        # As of October 2019, the Web shards needed more than 6G of RAM.
-        CPU: 2
-        MEMORY: 8G
-      compile_host_script: |
-        cd $ENGINE_PATH/src
-        ./flutter/tools/gn --unoptimized --full-dart-sdk
-        ninja -C out/host_debug_unopt
-      fetch_framework_script: |
-        mkdir -p $FRAMEWORK_PATH
-        cd $FRAMEWORK_PATH
-        git clone https://github.com/flutter/flutter.git
-        cd flutter
-        bin/flutter update-packages --local-engine=host_debug_unopt
-      script:
-        - dart --enable-asserts $FRAMEWORK_PATH/flutter/dev/bots/test.dart --local-engine=host_debug_unopt
+      << : *REGULAR_TASK_TEMPLATE
 
     - name: web_tests-6-linux
       only_if: "changesInclude('.cirrus.yml', 'lib/web_ui/**', 'web_sdk/**') || $CIRRUS_PR == ''"