refactor(platform-browser): reduce runtime code size of shared style host

The `SharedStylesHost` class has been refactored to both reduce the runtime
code size and also modernize some of the code structures. The class is also
adjusted to better support reuse via subclassing or other reuses in the future.
Additional comments have been added to improve readability as well.
The code reduction in a prerelease newly generated Angular CLI application
for production is ~410 bytes.

Before:
```
Initial chunk files   | Names         |  Raw size | Estimated transfer size
main-GOQKBZBZ.js      | main          | 208.67 kB |                56.41 kB
polyfills-FFHMD2TL.js | polyfills     |  34.52 kB |                11.28 kB
styles-5INURTSO.css   | styles        |   0 bytes |                 0 bytes

                      | Initial total | 243.19 kB |                67.69 kB
```

After:
```
Initial chunk files   | Names         |  Raw size | Estimated transfer size
main-CRTDDKPH.js      | main          | 208.26 kB |                56.32 kB
polyfills-FFHMD2TL.js | polyfills     |  34.52 kB |                11.28 kB
styles-5INURTSO.css   | styles        |   0 bytes |                 0 bytes

                      | Initial total | 242.78 kB |                67.61 kB
```

Author: clydin

packages/core/test/bundling/animations-standalone/bundle.golden_symbols.json

@@ -1355,6 +1355,9 @@
   {
     "name": "remove"
   },
+  {
+    "name": "removeAll"
+  },
   {
     "name": "removeClass"
   },

packages/core/test/bundling/animations/bundle.golden_symbols.json

@@ -1430,6 +1430,9 @@
   {
     "name": "remove"
   },
+  {
+    "name": "removeAll"
+  },
   {
     "name": "removeClass"
   },

packages/core/test/bundling/cyclic_import/bundle.golden_symbols.json

@@ -1157,6 +1157,9 @@
   {
     "name": "remove"
   },
+  {
+    "name": "removeAll"
+  },
   {
     "name": "removeFromArray"
   },

packages/core/test/bundling/defer/bundle.golden_symbols.json

@@ -2405,6 +2405,9 @@
   {
     "name": "remove"
   },
+  {
+    "name": "removeAll"
+  },
   {
     "name": "removeFromArray"
   },

packages/core/test/bundling/forms_reactive/bundle.golden_symbols.json

@@ -1724,6 +1724,9 @@
   {
     "name": "remove"
   },
+  {
+    "name": "removeAll"
+  },
   {
     "name": "removeFromArray"
   },

packages/core/test/bundling/forms_template_driven/bundle.golden_symbols.json

@@ -1691,6 +1691,9 @@
   {
     "name": "remove"
   },
+  {
+    "name": "removeAll"
+  },
   {
     "name": "removeFromArray"
   },

packages/core/test/bundling/hydration/bundle.golden_symbols.json

@@ -1268,6 +1268,9 @@
   {
     "name": "remove"
   },
+  {
+    "name": "removeAll"
+  },
   {
     "name": "removeDehydratedView"
   },

packages/core/test/bundling/router/bundle.golden_symbols.json

@@ -1964,6 +1964,9 @@
   {
     "name": "remove"
   },
+  {
+    "name": "removeAll"
+  },
   {
     "name": "removeFromArray"
   },

packages/core/test/bundling/standalone_bootstrap/bundle.golden_symbols.json

@@ -1019,6 +1019,9 @@
   {
     "name": "remove"
   },
+  {
+    "name": "removeAll"
+  },
   {
     "name": "removeFromArray"
   },

packages/core/test/bundling/todo/bundle.golden_symbols.json

@@ -1373,6 +1373,9 @@
   {
     "name": "remove"
   },
+  {
+    "name": "removeAll"
+  },
   {
     "name": "removeFromArray"
   },